tino said:
This is not a bad idea.
I like the idea of a swivel screen, though.
My history was this:
350D -> 40D -> 7D
I made the jump when I felt I got a lot out of the upgrade. My personal preference was also to jump 'up' in model tier. I always felt that moving to a better version of the same tier wasn't really moving forward as much, as you're mostly getting incremental upgrades, as opposed to something that will give you new challenges and open up new avenues.
For example, my transition to the XXD series was probably the more important leap, if not only for the control dial on the back, as I was a predominantly Manual exposure shooter. The more robust body and increased FPS opened up new types of photography. Also the new processor inside allowed much easier manipulation of my settings.
My move to the 7D was pretty big also, mostly for the jump in MP. I was always of the opinion that better quality pixels vs. number was important, and that's more or less true, but the 7D represented a leap in quality AND number. It really has changed my photography.
That said, the move to a 600D from a 350D is huge - all the advantages spec-wise that you'd get from a 60D you'd be getting in a 600D too. I still think the non "spec-related" improvements such as body, viewfinder, and extra dial are very important advancements.
Don't be fooled into getting the latest and greatest, though, as they may not represent the best bang for your buck. Get something you have enough room to grow as a photographer, but not something that you're going to pay more for, but only use the extra features when you're going to feel like upgrading at that time anyway. Something like a new 50D would be worth looking into, assuming they are considerably cheaper now that the 60D is out.