The 10x7 3 blade is the same diameter as the 10x7 2-blade so ti will cut up just as much grass.

You'll also suffer in performance since the 10x7 3-blade will be harder to spin than the 10x7 2-bladed. You'll want to drop in diameter and/or pitch when going to the 3-blade.

I've also read that 3-blades are generally less efficient than 2-blades on small aplications liek RC planes. I can't personally verify that though since my 3-blade experience is limited to briefly messed with a couple 3-blade props on small electrics.