Bluefish, I like your work-coat-over-a-suit analogy and totally agree with it (the only gear outside of my pack are wet tent/clothes).

The Lightning has a pocket within the main compartment, stretchy side pockets and hip-belt pockets. While it lacks a front pocket, the intriguing compression system seems more functional: you can lash wet gear and/or compress the front of the pack for a thinner profile. The straps can be laced in different ways depending on your needs (criss-cross, vertical, horizontal, etc).

Other pros and cons in my eyes:
+ A lot of mod potential (swapping out compression straps, adding bottom bag loops or front pocket, etc.)
+ Roll-top can be sealed in two different ways (affects ease-of-access, compression, and water run-off)
+ Single seam that runs around the bottom of the pack (better waterproofing, less seams to rip)
+ Aluminum stay can be bent to the curvature of your spine
+ Adjustable torso height
+ Not too many pockets and zippers to distract me from packing light
+ Very light (2lbs) but with support
+ Sizes are bigger than advertised: the 45L is more like 50L and the 60L is like 65L
+ Strap tidies: not a dealbreaker but I don’t like the messy-hanging-straps look
+ Unusual appearance and rarity (in my area) contribute to ‘style’
- I never see the pack in any local stores so I’ll have to order it online (obviously with return policy)
- Hip belt and lumbar padding seem excessove
- The kinda-internal-kinda-external frame looks uncomfortable but reviewers seem very comfortable with it
- Can’t decide which size pack to try first

As for the Atmos, I loved the fit of the pack, but… (1) The curvature of the main compartment might be difficult to work with. Is this true? (2) It’s design is too complex for me to mod and personalize. (3) It’s the typical common ‘hot’ pack right now so it lacks uniqueness. (4) Some of Osprey’s design sensibilities are questionable IMHO- too many zippers and pockets and straps; too much weight. But the pack looks good overall. And it’s available at a local store with lowest-price matching. And I’ve never tried any other pack that felt like donning a pair of wings.