I am thinking at 6'1 it will be a small bike and maybe uncomfortable, however its a great starter bike. As for the 550, my brother in-law also 6'1 took it for a ride and wanted to buy it from me, so he found it was quite comfortable ride. Its also going to depend on if its going to be ridden out on open roads or in the city, a 350 in the city may just be perfect.
.: Scott :.