Welcome to the forum,
If you're on the fence as to what to do or who's right - the best thing is to get more opinions.
Probably the easiest way to do this is to contact Mark Mintzer, the founder of this forum at
GPN Artificial Disc Replacement ADR. Though his website, he can put your films and history online and have an internet consultation with the best doctors. There is a cost involved for this service but is probably the quickest way to get another opinion.
A word of caution - do not make a decision until you're sure of both which doctor you want and which procedure. You mostly have 1 chance to get this right and only you will reap the reward or suffer the consequences.
That being said, fusing S1/L5 isn't as bad as fusing L4/5, which we're assuming is the recommendation.
Good luck, Dale