If the Exos is working for you, carrying what you need comfortably, and at the end of the day you didn't notice the pack (no soreness, etc)... they I wouldn't mess with it. The only reason to change it would be to chance the elusive (least possible weight) which isn't that productive.
My personal experience was I found the Gorrila more comfortable than the Exos... but everyone is different.
Over the years I experimented with a lot of backs. Under <12-14lbs pretty much anything but a really badly designed pack works ok. If you are shooting for the lowest possible carry weight, and you have only 1-2 days of food, then sure, doing some 3oz minimalist pack lets you squeeze those last few ounces out can be cool.
My experience, your's could variety, is than when I got to around 14lbs something changed. That from that point on, I would happily carry an extra 1-2 lbs for a pack that has some sort of frame... it was just a lot more comfortable. I found that up to around 25lbs, the "frame" system could be fairly basic. The plastic framesheet in the GG Vapor Trail, basic stays and sit pad in the Gorilla, packs from SMD, etc. Above somewhere between 25-30lbs, the pack really need a good frame system or I would notice it at the end of the day.