Hello, Jeff. So sorry to see you here. I know your diagnosis was a real shocker.
Your urologist is right on both issues. And referring you to Dartmouth was right also. You want to be at a place that sees and treats a LOT of bladder cancer cases and where they are up on the current best treatments. I am not familiar with a lot of success with bladder preservation with the type of cancer that you have. I am familiar with several cases where the attempt was a big mistake. What is more important, your bladder or your life? This IS a topic that you should discuss with the oncologist/urologist at Dartmouth.
As you are healthy and relatively young, even though cystectomy is major surgery, you should do well. We have members here who have had a cystectomy who drive race cars and even scuba dive! Yes, there are things that will be different, but you can have a very good life.
One of the things that you and your team will need to decide is which of the three major types of diversion you will have. Here is an excellent summary of the basics of all three:
my.clevelandclinic.org/health/treatments/12546-urinary-reconstruction--diversion
Wishing you all the best
Sara Anne