We've only had great experiences. The only thing that would get us to sell our SSR contract is if we start not being able to use it anywhere else. We love VAK, so even if we were "stuck" there, I don't think we would sell.
As it is, the only times we haven't been able to get exactly what we want at 7 months (or less), we've gotten a second/third choice that we are very happy with. Like for our upcoming trip, we managed to get a Treehouse for 5 nights during the week before Easter at 4 or 5 months out. And while we weren't able to get BLT or BCV for the remaining 3 days of that trip, we did get BWV after about a week on the waitlist.