I've done quite a bit of research on Dr. Sigesmund and have thought about contacting him myself.
I've been seeing Dr. Rondeau for about a year, and have received a small amount of relief. I do think I'm an exception though. Marlene, who also frequents these boards, went to Dr. Rondeau and had great results. You're right though, Dr. Rondeau has started concentrating his time on teaching other dentists how to make money by treating TMJD. If it wasn't for his assistant who deals with me most of the time I probably would've switched dentists long ago.
Yes, once you begin splint therapy you'll need to go back at least monthly for regular adjustments.
Again, I don't know anyone who has seen Dr. Sigesmund, but I would really like to know how you make out if you do contact him.