We have rented several of the 600s along with the 800s, and while they work just fine, there is NO DOUBT but that the 800s are WAY MORE FUN to ride!By the sounds of the type of rider you are I'm sure that 600 would put a smile on your face every ride.
For me the cost is NOT the main issue.
I am just trying to be carefull and make the right choice the first time around.