From my experiences with trikes on grass, the nose wheel tends to get the prop in the grass(Apprentice comes to mind), so a larger one is sometimes needed on certain planes.  While not a problem, as it helps in take offs, landings though, if you do a 3 point, or slightly nose down, it will dig in and cause a not so good landing.  

However I feel a taildragger makes you a better pilot in the long run. It is prone to ground loops and keeps you on your toes during transition from tailwheel to rudder on takeoff, while trike makes for better ground handling.