Ok....you got me with the burying threads part!!
I HATE that! I still can't see that changing out the bobbin while on a frame would be any different than any other machine on a frame, other than the frequency. I had that Pfaff on a frame...just ran it down to one end of the frame off the quilt and changed the bobbins...
Truth be told, unless it's a longarm that gives you a lot of space, I don't think frames for machines are worth the space or hassle...but that's strictly a personal opinion/preference!