No comment on the bag itself (I run my own designs that suit my preferences better) but I ran the guidelight frame all last year. For my body I think <90lb is comfortable on that frame, over that I have the belt bottomed out which is just due to where my waist size falls vs their belt sizing. On the subject of belt sizing I find their assigned sizes completely unrealistic to our uses, maybe they are accurate for 40lb backpackers but for myself and friends that have used them they were too large for the range published. IE at a 33-34waist their 29-34 belt works for me up to 90lb at which point I bottom it out, my 31waist buddy would bottom out that belt at a much lower weight. He ends up using their <29 belts. So that's a long winded way of saying if you are on the lower end of their published belt size go down a size.
Main tidbit I learned on that frame is the lower corner straps MUST be tensioned to something that pulls backwards on them somewhat otherwise the frame corners flex and it slips on me, but with those tensioned it works just fine.
Other thoughts: The height of the frame tower and width on my body works well that it provides proper lift w/o feeling the frame off to the sides of my ears/head so its more comfortable to walk around in for me versus a taller/stiffer/wider frame tower. I disliked that they went away from PALS on the belt and the fact the belt strap slipped if stuff was hung on it when unbuckled, but I made PALS sleeves to solve that and have been happy on that front since but do wish they had just designed it in off the bat. At times I've thought it would be nice to add a couple extra side loops to have a second set of straps to strap down a load independent of the bag, I just haven't gotten around to it (technically with the open frame it doesn't even need to be attached can just loop a longer strap around the frame rods). Yoke adjustment is pretty simple on the pack and once dialed in under load fits me well.
That's all off memory.