The "Plus" version of the tire is definitely going to be a rougher riding tire.
I use the regular Marathon Winters. They're about 5 years old. They're the fastest best riding studded winter tire I've used...I'm a bit perplexed about some of the claims of bad ride quality. They are, of course, not as nice riding as my pure rubber summer tires. I don't have grip issues on dry pavement either...my opinion is they lose about 20% on dry pavement but in my experience the only thing that limits is throwing my bike around aggressively which I don't really do in winter riding anyways. Mine have held up well as well, better than the nokian 160's I put on my brothers bike. Schwalbe have lost a random stud or 2, compared the the w160's that lost maybe 4 studs in a row and I'm hesitant to let him keep using now because of that.

In the summer I've used the schalbe marathon supreme's. For a tire wider than the 25c-28c category, I think it's a great tire that really doesn't have any flaws at all. Grips well in the dry, and the wet. Rides well. Seems to last a long time. It seems to lack any drawbacks at all...except the price, at like $80/tire it should be a nice tire right?

The "regular" schwalbe marathon's that cost $30-$40/tire I've heard mixed things about. Perfectly fine tire for the price, but kinda slower and rougher riding - not "bad" but certainly not as good as the really good tires.

On my summer bike I've ridden gp4000's - everything is great about them except the ride quality is a bit disconnected from the road. I switch to use Specialized Roubaix's Pro's and they've been the most comfortable bike tire I've used (in that size):
https://www.specialized.com/us/en/ro...=230998-156469