I took the plunge and bought the Schwalbe Big Apples for the front two tires. After contacting Utah Trikes to get the status, they replied quickly informing me that the tires should be here tomorrow! I just ordered them on 8/13/10. Pretty good ship time.
I can't wait to put those suckers on. I'm expecting the full benefit of the lower rolling resistance all around. I'll be nothing but disappointed if I don't get the 2mph speed increase I've been so desiring for the last month or two. Only time will tell. More reports tomorrow if the weather improves.