I run a 38 tooth on my 700x42 wheel/tire combo, which is like a 34 tooth sprocket on a 26" wheel and it pulls me along just fine. As Damien said, it makes it a more useable and tame machine. Would I rather run a 40 or 44 tooth on my bike? Yes, but compromises had to be made. It's not weak by any measure and still pulls stronger than a typical 66cc with a 44 tooth on a 26 inch wheel while also sitting in a perfect RPM range for cruising around at speeds appropriate for a MB (around 30-35mph). Yes, it can go faster, but I don't really care about fast. Benig at half-ish throttle at 35mph turning 6000ish rpm helps keep the engine running cooler and returns some incredible fuel economy (over 100mpg). Probably the best fuel economy I have ever experienced on a MB, ever.
If you use the Phantom's saw based cylinder design for it's real strength - the delivery of strong torque in the lower and middle RPM range - it delivers awesome performance. Saw's pull hard under high load for a reason.