I have Q-snaps that I use for several projects. Can I assume by "damage" you mean crushed stitches? Part of the problem with using hoops is that first your fabric is bent at a sharp 90 degrees, then is compressed and then pulled; that's a lot of stress in a small area. With the Q-snap, the bend radius over the pvc is nowhere near 90- degrees - it's an arc. And because the contact between the frame and the clamp of the snaps is such a large area, compared to a hoop, the stress of the compression is spread out so much more, so it doesn't leave marks.
Now, I'm lazy, so one of my projects that I am doing in my 11x17 snaps (I think that's the size), I fold up my excess fabric and put it under the clamp, so I do end up with creases at the end of the week, but I also crease my projects when I take them off and put them away until next rotation, so I do pretty much iron these projects each time I'm getting ready to put them in the snaps. Also, most of the projects I have done using snaps, the two sets I have are big enough to accomodate the entire stitched area inside the frame, so it's not an issue.
I have my SQ on a sroll frame - I made a custom-width one for this project by getting a couple of oak dowels from the hardware store, and putting them into the side rails from the store-bought set. This is going to be an extremely long-term project, and I do not have any problems leaving projects on scrolls indefinitely. Using Q-snaps might be okay for a big project, but I personally would hate having to contend with all the extra fabric, so scrolls is my choice.
Get a couple of sets of Q-snaps, and give them a try. I need to get a small set - I am using the dreaded hoop on the ornaments I am working on, and I realllllyyyy don't like hoops any more. The last couple of times Hobby Lobby has had Qs on sale, they don't have any of the 8x8 or 10x10 (again, I may be making those sizes up) left by the time I had time to go. And, after a while, if the clamps lose their tightness, like anything plastic, they go through a dishwasher cycle, and the heat of the water (I don't use the heated drying cycle) makes them tight again! Can't get much more convenient than that! I also have the cheapie unversal floor stand from Wal Mart, which accomodates Qs and my scrolls the same way. Get a set - they may not work for every project, but I bet once you use 'em, those old hoops will go right into the trash (unless you keep 'em around for emergencies, like I do

).