npan- I don't hate you... I totally understand. And to all these people that say 400's suck and all that, I loved my Z400 and for the trails you can only go so fast anyways. The Z is a great bike and will beat on the 400ex's you ride with. I wouldnt worry about spending the money to get a 450.
That being said I think that I enjoyed my Z more than my R, the R is more of a rush to ride, just a little more work required. Keep the blaster and save up for another bike...doesn't hurt to have multiples!