I have a '17 Sidewinder, which I love. I have not had any issues (knock on wood), but I also had read about some issues others had when they first came out. So, there were a few things that were done for preventative maintenance. If you do go this route, I would suggest taking a look at the Sidewinder forum on Totallyamaha.com (hopefully it's ok to mention another website on this one.) It will provide you with very comprehensive info about this model and what potential issues and fixes may be. Just like anything else, some products have good and bad, even within the same production line. My brother has the T-cat version (same year.) He has not had any issues.
I guess it also depends what you're really looking for. Are you wanting one of the fastest production models made that may come with extra need for maintenance or care? Or are you just wanting a good reliable sled? Normally, the more HP, the higher the need for care and extra maintenance. I cannot speak for the Doos mentioned, but have heard both good and bad. Again, any brand will have issues at times. Good luck.