I built my GT500 over the years to get it to almost exactly how I wanted it to be all along. I was in love with it! For a few weeks. Now I look at it and think, hmm... Welp, might be time for something else. The difference with mine is that it's not "undriveable." The biggest (and probably only) annoyance I have with it is the SPEC Super Twin clutch. Pulling from a stop with that thing certainly takes a lot of fun out of it. It would probably be perfection if I switched to something more street friendly. A couple weeks ago, I was driving around Chevy dealerships looking for a ZL1 1LE. Apparently, they aren't available for sale yet.
Anyway, you're definitely going to regret selling it initially. Then you'll get settled into the new car and won't miss the old one as much. A few months/years later, you'll get hit with a longing regret for your Mustang. I still have my GT350R, but if I sold/traded my GT500, I'd probably miss the hell out of it the whole time. She and I have been through a lot together. She's been with me for over 7 years. Heck, I still miss my '05 GT sometimes and wonder where it is.
Anyway, you're definitely going to regret selling it initially. Then you'll get settled into the new car and won't miss the old one as much. A few months/years later, you'll get hit with a longing regret for your Mustang. I still have my GT350R, but if I sold/traded my GT500, I'd probably miss the hell out of it the whole time. She and I have been through a lot together. She's been with me for over 7 years. Heck, I still miss my '05 GT sometimes and wonder where it is.