I too bought the Shock Doctor Power compression short with bioflex cup.
Works spectacularly. For both Grappling and striking.
I've used it primarily for muay thai and judo, on the ground when I have used it I barely notice it's there after a few minutes. It does hold up well to accidental low blows (though in a fight you *might* want to purchase the metal insert on mmawarehouse.com for it, just my personal thought)
As Deadmeat said, the quality thus far is spectacular, I wash it every 2 weeks, still no problems yet, stitching and material is holding up amiably. It feels appropriately tight, yet not constrictive. In a word, it's perfect as far as cups I've used. (Comparing to having used a TKD style jock strap cup, and a boxing groin protector)
For $30 it might seem steep in comparison to to say a regular run of the mill cup, but I can assure you it's well worth the $. Same goes for the shock doctor mouthpiece I'm using.