Personally, if you are going to be doing anything larger than lap quilts, I think the Flynn system would be just as frustrating (if not more so) than just quilting on your DSM.
I have a longarm, and have not regretted buying it for one second.
Yes, they take up a lot of room, but I actually had mine set up in a single-wide mobile home bedroom when I first got it. Granted, it was the ONLY thing in the bedroom, and I only had room to get around it on one end, but I never regretted getting it.
With that said, before you buy ANY longarm or other quilting system, go to one (or two) of the larger quilt shows and "test drive" EVERY THING. I looked, tested, looked some more, tested some more - for 3 years!! - before I actually bought my machine. I was not just looking at the price, although that was a partial factor. I bought the one that moved the way that felt most comfortable for me, had the "have to have" functions, and fit what I felt I could afford.
You should check at your LQS's too, and see if they rent time on their LA. Some do, some don't. This would give you a better opportunity to learn if this is really what you want to do.