Welcome to the site! The biggest difference in performance between the two bikes is the Speedmaster stops harder because of twin front brakes. The older models had the Speedy geared lower as well, but I think it's the same on new models. Get the one that fits you best, and have a blast. I would also recommend reading all of the Riding Technique posts, there's a lot of experiance tied up in there.
Steelheart- '03 Speedmaster Black/Yellow
The Hayabusa Killa
16" Shorties/140 mains/Airbox drilled
Procom CDI
"There is no cure for Celibacy. But we can treat the symptoms."