I'm so glad I read this thread this morning! I'm in the same (almost) predicament as you are...been looking at 2SS/RSs for a couple of months now and would love to get one. I really love my V6, so I don't HAVE to get rid of it, I've really personalized it and made it mine, but since I drove the SS, I do like it a lot. Can't seem to get the deal I want with two that I've driven and liked. Working on a deal with another one right now, but I'm not sure if I should do it right now. I'm not upside down, but I'm leaning toward just paying off my V6, then getting an SS; however, my mileage is climbing, only making mine worth less. I did find that when I took an SS home over a weekend awhile back, that it took A LOT more gas than my V6 which is a concern since I will be moving soon and my commute will be longer. Did find out tho, that my insurance would actually go down a bit.
So, I'm back to being on the fence like you...good luck with your decision.