I'm in a bit of an opposite stance from most on the forum. I switched from having a Genie and multiple HR24 HD-DVR to using the Genie Mini's and I am satisfied.
Yes they are slightly slower, and yes I can only record 5 things instead of 9. But I much prefer having the access to the to-do list, series list, etc from any room and not managing multiple DVRs.
We occasionally have a conflict, but with 5 recordings it is pretty rare and the bumped one is usually a repeat series in syndication that gets recorded later in the night anyway.
I have a C51 and have been happy with its performance. A few years ago when mini's first came out I bought a C31 and was not satisfied with it (very slow). I returned it after only a couple weeks.