The wheels being 16" is probably so they can use the same gearboxes, wheels and belt drives across thier range of saws. A larger wheel would require lower gearing. I too would have expected the weight to be much higher though.
My doall came with a 1hp motor, but at 550v it was no good to me. I swapped to a 2hp 240v 3 phase with a vfd, ditched the reaves drive and just use the gearbox in low. Nothing slows it down.