Photographs taken from various angles would tell us a lot more as to whether it's the pack style or just the adjustment or wrong pack size that is the problem. Load up your pack and find a volunteer to take the pictures! At least front and side views, and some at an angle that shows the strap problem.
Read the recent State of the Market articles on frameless packs and the ones from last fall on lightweight internal frame packs for lots of insight into pack selection and fit. I'm not looking for a new pack, but I found these articles extremely helpful, especially in adjusting packs for my grandkids (who of course need pack fit adjusted every month or two).
I have extremely pressure-sensitive shoulders and require load lifters (which should be at a 45* angle to your shoulders--not all of them are) to be able to carry even a 10-pound pack without agony. I thought it was just old age, but my 11-year-old grandson has exactly the same issue. The load lifters keep the shoulder straps from cutting into the tops of my shoulders as well as transferring more weight to the hip belt. I noticed in the pictures of the Granite Gear packs in the internal frame pack SOTM that the load lifters are at a very poor angle, so I wouldn't even consider one. This may not be your problem, though, which is why I suggested photographs.
Keep looking! You may have to try lots of different packs (including paying return postage on packs you have to order) before you find the perfect pack. It would be a good idea to discuss this issue with the pack manufacturers before ordering.
If the Gregory pack is really comfortable for you, you might be able to trim as much as a pound off it if you can stand to do some creative butchery. Just be sure to try it on over all your insulating outer clothing before shortening shoulder and waist straps! Also, be sure to hem the strap ends that fit through sliding buckles. I discovered at the trailhead last week that I had lost half of my waist band buckle because I didn't do the hemming bit. Somehow, a square knot just didn't do as good a job!