I think about this A LOT. I would swap with a GG even if I knew she was going to live only 2 more days, so that I would know the happiness that's always eluded me. I had this thought just today in fact.
I saw a FTM the other day at a doctor I go to who specializes in transgenders. He was only distinguishable to other TGs I think, as I spotted him right away. He seemed like a pretty rugged guy with facial hair and a voice deeper than mine. I thought, if only we could go back and swap brains somehow. Hopefully it was easier for him than it is for me.
I also have the thought: to be the woman I think I should be right this very second, I would give up everything I owned or would own, and walk away from all family and friends I ever knew forever. As old as I am it would "wipe away" any time I've lost. I've been on this road long enough and have tough times ahead with FFS, legal changes, etc. So if something scientific came along like a body swap, I'd be the first in line.