I have had my 6600 since 2005 and never regretted the decision to buy it once!
I would have the same expectation of the 6500 so you have chosen well as far as i am concerned! You get a lot of “bang for your buck” with Janomes - and the bigger machines like the 6500 and 6600 are real workhorses that wont let you down as long as you do your regular cleaning each time you use it.
Although i’m sure its not “recommended”, i have never yet had occasion to have professional maintenance done on mine. I have had no problems, but if i do i know where to take it locally to get it looked at if necessary - that means a lot to me! Congrats on a great machine!