Both generally top out around the same speed, but the 1300 will kick fuck out of a 650 on performance, 0-60, etc. Even the 1100 is noticably more beast with 20 more horses and less of a percentage increase in weight.
I go as fast as is practical, I am able and is sensible at the time.
I am often accused of treating my Cruiser like a Hoolie Bike, mainly by the comparatively sedate other half... I do outride a fair few bikes that should be whipping me, though. It all depends on my mood - I like slow, controlled corners and scraping the pegs at 10mph. The best feeling is getting a corner perfect!