Using my 300D I installed the Russian Hack with gave the camera mirror lockup, best thing I did for my camera. That's imaging on a G11 mount. With my newer 20D the mirror slap is much more pronounced. Unfortunately the standard remote timer doesn'7 seem to work the mirror lock properly, I've had it modified.
Hopefully when I get it computer controlled I'll have another work around.
The bottom line: If you can get mirror lockup, use it.
btw I was under the impression that the 10D had mirror lock. The Russian Hack for the 300D gives the 300D the same functionality as the 10D.