I have always firmly believed that there is more fun to be had from riding a slow bike quickly than riding a quick bike slowly. Whenever I've had a bike with a bit of power I end up either getting frustrated at being stuck behind slow moving traffic or scare myself when my enthusiasm overshoots my ability.
The other day I had a ride along the Via Gellia in Derbyshire which is a well known biking road and the Mighty Midget was flying, all of 55 to 60 mph and it felt brilliant. I've been along there when I had my 1100 BMW at a similar pace and just got fed up with 'dawdling'. I am a confirmed sub-350 fan and have recently been more attracted by mpg than mph.
Spartacian the impecunious.