I have had a SR2 frame for about 2 years now. I have a brother pq1500 9" on it. All I could afford. The frame is solid but. Couple of points. The hardware is not a hard grade and you will wear out the threads raising and lowering the bars. Suggest you get a good rubber washer and put it behind the metal one provided. That makes it grip to the metal frame and then you don't have to crank so tightly on the screw threads to get it to hold. My first set of Hardware lasted about 5mos.... Second set with washers I have had 1 1/2 yrs. also you have to pull out on these pegs to unlock it from the wratchet teeth. Support the bottom of that bracket when you do this and that will also help maintain your hardware. Now having only a 9" means I do a lot of rolling also. You can do about a 82" wide quilt comfortably. You can get 88" to fit but you will be carriage to end of frame on the borders. Doable but not comfortable also not enough room to get to bobbin area. Now length is no problem other than with the floating top you have the top and batting bunched up on the floor. Also those white clips will not work on a large quilt. They do not open wide enough to fit over the backing roll and batting and top. But you don't really need them until you get to the end. I have taken my quilt out and reloaded the side so I could do the borders complete and not have to do them in 9" sections. That does work but I don't know how you would do that side-to-side for a wider quilt. I would say either go with 2 sections and piece or maybe do side borders on dsm.
i went to the frame because using a dsm and moving by hand was very hard on my hands. Being able to move the machine only on the frame is much easier on my hands. Carriage moves freely most of the time I use one hand with no problem. If you have a space problem I put one end by the doorway which gives me the ability use that walkway as easement for working with the bar adjustments. I have about 8" of space on the other end and it is enough to reach and raise or lower the bars and I have short arms.
it is a solid frame and goes together very easily. I would go with th largest throat space I could afford. I would give up frame size for throat space. Wish I could have afforded a 15" but at least I know I can go to it someday. 9" isn't ideal but doable you just have to plan more where you are going to stop and start.