I think I got a call from the same company a couple of years ago? My motor was still in a one year extended warranty via Yama at the time. They indicated that they included parts that were NOT included in the extended warranty - items that Yamaha did NOT cover.
I DID discuss with my local dealer but I can't remember

what the story was? I just recall it didn't sound like it was worth pursuing. I DO trust my Yama dealer enough to take them at their word!
Do as you said and talk to a few service shops about their experience with the company. Even if it's "positive", I'd STILL check with your BBB and see what they had to say!
I'd think there a some here (as BIG as we are!) that have had dealings with this company?
I know that you CAN get a "used warranty" from Yama (not sure what brand motor you have?) that applies AFTER the end of other warranties, but I think the motor has to be "checked out" FIRST by a Yama service shop (I think at YOUR expense) to see if it's "warrantable"(?), and that the warranty itself is pretty expensive!
Good luck and keep us posted as to what you find out!
Regards,