Happy to share my experiences with both the Flash and the Hornet. Both are excellent packs overall, but not without some shortcomings.
I've used the Flash 65 a lot (and the 50 a little), not the latest version, but the last one before it. I prefer it without the framesheet, which didn't feel all that good on my back, and which didn't seem necessary even up to ~ 30 lbs or a bit more. Shoulder straps are nicely padded, hip belt functions well, and even without the framesheet, if you put a light foam sleeping pad against the back and pack things nicely, it has decent structure. Things get a little "squishy" as the load shrinks, but by then, it's lighter. The Flash 50's very similar, but not that much lighter. Sure, with a load that's a little smaller, it packs nicer than the 65, but I'm not sure it's worth having two packs for the minor difference and may not keep it.
I've had good experiences with Osprey before, and the Hornet 46 seemed like it'd be a near-perfect pack for 25-30 lb loads, with the Delrin rods giving it enough structure to carry that load a little more comfortably than the frameless packs. In practice, it didn't really achieve that, at least for me. The shoulder straps were fine and the frame gave the pack a nice structure, but things broke down when it got to the hip belt. The belt itself seemed adequate, but I couldn't get any appreciable weight transfer to it, in part because of the belt's low rigidity throughout, but especially because there didn't seem to be any functional connection between the hip belt and the rest of the pack. When positioned normally such that weight might be transferred to my hips, the pack tended to sag until it was pulling from below the hipbelt. Unsurprisingly, this was not super-comfortable, but it also had the unanticipated effect of causing an apparent increase in my torso length with increasing load (relative to the pack's nominal length). I've noticed more than a few comments about torso length and fit for the Hornet, and wonder if this might have happened to others, too. I'd advise trying it on with a load similar to your maximum load to be sure that you won't have the same problems. If anyone has a solution to this problem, I'd love to hear it, because I was otherwise very pleased with the pack.