I use no-sparge quite routinely. I get 75% mash efficiency from no sparge and 85% from batch sparging. It'll depend on the size of the grain bill and your conversion efficiency.
I can't say I've noticed a huge difference, but you can make a great no-sparge beer with decent efficiency. I make my pale lagers with no-sparge to try to minimize tannins, and I'm very happy with the results.