Go with larger wheels. My experience has shown that MOST 46 size planes need 3" - 3 1/4" wheels to fly from a grass field. Make sure you replace ALL THE WHEELS, not just the nose wheel on your nexstar. Replacing just the nose wheel will make the plane take off before it has adequate airspeed to fly.

As for the 3 blade prop - If you ABSOLUTELY NEED IT fine, however, 3 blade props are not only more expensive than a 2 blade prop, but they are less efficient than a 2 blade. I have used a 3 blade on a couple of occasions - on one occasion I had insufficient ground clearance and redoing retracts was not an option, the other occasion was for a scale appearance. In the second case the prop was replaced after one flight with a 2 blade prop (3 blade 10x6 -> 2 blade 11x6 ). The difference in performance was like night and day.