I have the XP5 Ultimate and got the Polaris Canvas uppers. The only times I use them is in the winter to help cut the cold and wind. Even at that I typically have at least the driver one rolled down for fresh air. I don’t think I’d want the hard poly ones, just for that reason.
The Polaris uppers are definitely expensive, but I’m really glad I got them. They’re very sturdy in design and material, and considerably less expensive than full doors at around $8000 or Northstar upgrade at $12000. I’m perfectly fine with riding in the heat, it’s the cold I don’t handle so well, and just having the uppers in the winter is enough to make riding in the cold weather okay.