atsoca- Welcome to Autopia!
I use Griot's pretty much exclusively, and it's very gentle on LSPs. Sure doesn't compromise Collinite at all. Kinda pricey though. A less expensive alternative would be DuraGloss (which I haven't tried, but people I respec/trust like it). Somebody's gonna mention Meguiar's Gold Class (which I'm not all that impressed with, but it isn't *bad* stuff) or even TurtleWax ICE (which I haven't tried), both of those are popular OTC shampoos. Still...there's a reason why I'll pay through the nose for the Griot's, IMO it's simply the best shampoo on the market.
Dunno about the PolySeal, but IME Collinite isn't really shampoo-sensitive, it even holds up when I use touchless carwashes. I'd worry more about cleaning power and, *especially*, lubricity.