I use Sonus clay pretty much exclusively these days.
The gray can mar paint, even hard paint and even when used properly/carefully. I'd absolutely plan to polish aftewards. Note that I've clayed a zillion vehicles with a few different types of clay (maybe 6 different ones, didn't keep track) and the Sonus gray is the only clay that *ever* resulted in significant marring.
That's not a slam, just a caveat. It works great when you *need* the added aggressiveness.
The green is very, very gentle. Used properly I shouldn't mar, never has for me. It doesn't even cut through healthy LSPs if you use it properly, and just cutting through a Meguiar's glaze/"pure polish" with it actually took some doing!
I spot-clay as needed with Sonus green at *every* wash.
IME Sonus clays aren't always QD/shampoo-compatible, they can break down quicker than some other clay when used with that for the lube. They seem to work better with Sonus Glyde lube but don't let that put you off; just tear them into small pieces and get a new one as needed.
But be careful with that gray stuff. A while back, RAG sold me all of his Sonus gray because it was just too aggressive for him, and he deals with some pretty nasty contamination.