When considering which pack to carry, you have to ask yourself a few more questions than just comfort. Durability, features (side pockets, removeable toplids, etc), size, etc. should also be contemplated.

The Bora is one tough pack and will carry heavy bulky gear well. it is made to do heavy hauling when that is absolutely needed (i.e., mountaineering), but is not preferable on a 'regular' backpacking trip. Several of my married friends, who haul everything for the family, are, by necessity, required to use heavy haul packs as well. But it is not that comfortable for them.

I believe 'heavy' and 'comfort' are oxymorons. It may be true that due to the suspension of the heavy pack (stays, hip belt, shoulder straps) allows for a very supportive and stable beast due to the amount of thermal foam and heavy suspension involved, this does not mean that it's comfortable or something desirable unless needed. What you want is a compromise of durability, comfort, features and weight. There are many packs that would fit this bill, especially having all of this in a reasonably light package. ULA, Granite Gear, Mountain Smith all offer packs that are very capable of this. Even Kelty have a few packs (not familiar with the Shadow) that would work, although they tend to not be as comfortable as the above mentioned. Comfort, in my opinion, are those who maintain the required weight (in my case up to 30 lbs) without feeling like it is about to collapse. It needs to be both rigid enough and flexible enough to move with you while supporting the load. The hipbelt needs to be firm and supportive yet not cause abrasion (must not be flimsy). The backpanel (stays, plastic frame sheet, foam) need to work together to support the muscles and transfer the weight efficiently (not require the lumbar pad and hipbelt to do all the work). The shoulder straps should be firm and supportive in giving control over the pack while it's on me. I can get all of this in a 3 lb. pack that can carry 30 lbs comfortably at around 3800 cu. in.

I would look around before making my final decision.