CJ ~ I wasn't sure how to approach this one so I read back over your posts... for all you have been through with your life there does shine through one thing in you that may help you.
Regardless of all the bumps and hurdles you have a very stble and solid perspective on life. Should you undergo this radical treatment and the outcome be not what you want do you think that your eternal spirit will in the end help you through? its a simple but deep question, its a HUGE thing to undergo with many ifs so the only thing I can see as being yor safety line is yourself, that thing that defines you as a person. A lovely person. I'm sorry to hear this has come to a point that yo need to do something. I cannot fathom or imagine the magnitude of it.
Man, thats pretty difficult in itself. I haven't been through anything similar but my husband has. He had non hodkins lymphoma stage 3, his choice was to maintain quality of life with chemo (yep sure) or try a very new stem cell transplant. At the time the odds of him coming through that were less than 50/50 which seems strange when chemo would have kept him a live and err sick! anyway, they said the same thing, "you are young enough to be able to cope with this, later in life your odds get slimmer.
He took the risk and it paid off. I'm not trying to say anything here about your decision, thats totally yours, I wish you luck in making it though with a clear mind and a self awareness that may give you the opportunity to see a little further down the track than next year maybe.
Not easy and I am surprised by your outlook and the way in which you are approaching the whole thing, very mature CJ.