Well, now that you have seen the photos - it's pretty much a toss-up, right, so close yer eyes and pick one. That, of course, is an oversimplification, as I'll attempt to describe below, but they really are strikingly similar. As a preface to this comparative analysis, let me say that I'm happy to own one of each 
.
I'll make a few brief comparisons related to each of the following topics:
WEIGHT
Western Mountaineering Flight
WM stated weight: (size Medium): 5 ounces (142 grams)
TLB tested weight: (size Medium): 6 ounces (170 grams)
Feathered Friends Hyperion
FF stated weight: (size Medium): 7 ounces (198 grams)
TLB tested weight: (size Medium): 7.27 ounces (206 grams)
Note on weight variation: whereas the WM Flight is a standard, off-the-shelf piece, the FF Hyperion is a custom garment and will have variation in weight, depending on your selection of materials.
COST
Western Mountaineering Flight Vest: $150
Feathered Friends Hyperion Vest: $122
Note on cost variation: because the FF Hyperion is a custom garment, the cost will vary accordingly. The Hyperion tested here was $115 base cost for Pertex Quantum and an additional $7.00 for the optional 800-fill down.
MATERIALS
Western Mountaineering Flight
- shell: .9oz Polyester Taffeta
- lining: .9oz Polyester Taffeta
- down: 850+ fill-power goose down
Feathered Friends Hyperion
- shell: Pertex Quantum (taffeta is standard, other options e.g. EPIC)
- lining: Pertex Quantum (standard)
- down: 800+ fill-power goose down (750+ is standard, 800+ is optional)
FEATURES
Western Mountaineering Flight
- elastic drawcord bottom closure
- insulated hand pockets
- lightweight #3 Coil YKK Zipper
- down-filled draft tube behind zipper
Feathered Friends Hyperion
- large interior stash pocket
- insulated hand pockets
- large, generously-down-filled collar
- comfortable, top-zipper-cover chin-guard,
The color. The WM Flight comes in the color black. The FF Hyperion is a custom product and is available in a variety of shell types (i.e., Epic, eVent, Pertex Quantum and Nylon Taffeta) each with a variety of color choices (which frequently change). With the FF Hyperion you can't always get your first color choice. For example, when mine was made, the color black was available in the Pertex Quantum material. Now, however, if you wanted to get the Pertex Quantum shell you would have to order either royal blue or herb green. But the good thing is that you have some choices with the FF Hyperion (but you'll have to wait a month while it's constructed).
The Zipper. The WM Flight saves space and weight by using a small #3 YKK zipper which is backed by a down-filled draft tube effectively sealing out drafts. The FF Hyperion has a larger YKK zipper (not sure what size it is but the same size as my FF Helios vest). The FF zipper does not have a draft tube (or flap) behind the zipper. The FF larger zipper is easier to work with, especially while wearing gloves (of course, the zipper tab pulls on the WM Flight mitigate that problem).
FIT/SIZING
Some sizing information. First of all, I'll take the safe route and suggest that you should follow the manufacturer's sizing recommendations. For Feathered Friends, there is the Feathered Friends Sizing Chart. For Western Mountaineering, I could not find sizing information.
Okay, having gotten that disclaimer out of the way, I'll tell you my findings. The MEDIUM size, in both the FF and WM garments, fit me perfectly. By that, I mean not too loose, but yet enough space for full expansion of my chest without feeling confinement or restriction. I have a 37-inch (94 cm) normal chest size, and approximately a 40-inch (102 cm) chest size when inflated. Because I couldn't find WM sizing information, I ordered a size large and a size medium. I quickly discovered that the WM Flight size LARGE is too large. If you have a 40 inch chest, order the size LARGE. If you have a 37 inch chest, order size MEDIUM.
The Feathered Friends chart may well be okay for both garments if you are wearing only a lightweight thermal top with crew neck. In the pictures above, I'm wearing a red, expedition-weight Patagonia thermal top which has a high collar. The high, expedition-weight fleece collar was easily swallowed up by the FF Hyperion, but the WM Flight collar was a little tight on my neck. By the way, my neck size is a full 15 1/2 inches. You can see from the pictures that the FF Hyperion has an extra-large collar. On the other hand, if you are wearing underlayers which do not have an expedition-weight collar and your neck size is not a full 15 1/2 inches, then the WM Flight collar may be more appropriately sized for you. But again, the Flight collar works fine for me when wearing the crew neck style undergarment but is tight when I wear an under garment which itself has a fairly thick collar.
The Feathered Friends Hyperion is a little more tailored at the bottom compared to the Western Mountaineering Flight which has more of a straight cut. The Flight has the elastic drawcord bottom closure which gives it more flexibility since you can loosen or tighten the bottom according to your needs. Along the same lines, if you are shaped like a pear, the WM Flight would be the best choice for you.
The Feathered Friends Hyperion Vest is a larger garment. It is one inch longer than the Western Mountaineering Flight Vest in both front and back. The Hyperion has a little more down-fill.
WARMTH/COMFORT
Both garments have a comfortable, silky-smooth feel. Both are equally comfortable to wear. There are some differences.
The FF Hyperion has more down and being a little larger garment both at the top (larger collar) and the bottom (one inch longer in both front and back) appears to be a warmer garment than the WM Flight.
On the other hand, the WM Flight, because it has less down and is a little smaller, makes for a better mid layer in situations where less warmth is needed. (Did I mention that the WM Flight is also lighter and packs smaller?) One thing we shouldn't forget is that the WM Flight has the down-filled draft tube behind the zipper which adds to the Flight's capability to be worn as an outer garment.
The FF Hyperion has a nice built-in chin guard that acts as a little zipper cover as well. The WM Flight is very-well-designed and although it does not have a built-in chin guard, it doesn't need one. Both collars keep the zipper away from the face.
RECOMMENDATIONS
Both garments are top quality materials and workmanship. Both are comfortable and equally durable in the tested configuration.
If you're a big guy with a little neck, you might want to consider the WM Flight. If you're a little guy with a big neck the FF Hyperion may be more comfortable.
I don't have much more to say. Both garments are keepers. If you can get both, you'll find a niche in your routines that best suits each one. If you can have only one, then read through all the verbiage above, apply the findings, and make the appropriate selection.
One thing of note - the FF Hyperion is a custom product so you may have to wait a month to receive it after you place your order, whereas the WM Flight is off the shelf and if in stock, is available immediately.
For additional specification and purchasing information, go here Western Mountaineering Flight Vest and here Feathered Friends Hyperion Vest.
