I had more weight transfer to the hips when I used the REI Flash 50 in frameless mode. It was obvious that the framesheet was "bridging" across the hollow of my lower back, and would therefore slide a bit when I bounced while walking. Without the frame, I could suck the pack into my lower back much tighter - but with a slightly looser hipbelt (ie: not as much pressure felt on the front of my hipbones).
I think to get good weight transfer from a frameless pack, side compression straps (so you can turn the load into a solid lump), and a hipbelt that is very wide in the back (so it sucks the pack into your kidney area) are CRITICAL features. Without them, you need a pack that has a volume that forces you to stuff your gear VERY tightly, so it's a solid lump. Side compression is easier & more versitile (and could be added to your Flash 65 by any tailor).
On the Flash 50, I used a 48" Ridgerest as a tube frame, sleeping bag on bottom, food / kitchen bag next, inslated / camp clothing next, rain gear on top. So most of the weight was centered on my lower back (only light stuff above the bottoms of my shoulder blades). The flash doesn't have good compression, but this was a 65 liter load, stuffed into a 50 liter pack.
That said, the Osprey Atmos was more comfortable by about 25-33%. Not because of weight transfer though. It was because didn't press against my back or shoulder blades anywhere when I bent, twisted, or reached.
I also tried the Osprey Exos. It bounced a lot more than the Atmos, had a softer trampoline that bottomed out when I bent or twisted, and didn't allow me to compress the load anywhere as well.
Good Luck !