everything in my house is X10 controlled - I have no problems with it at all.
However, a few points to mention-
-Currently the CM11A support is broken. It has been fixed, but for whatever reason it has not been applied to the current SVN repo LMCE has been compiling off of. Hopefully they do this before 0710 final is released. If it doesn't make it into the official release, I will compile binaries with instructions on how to update them on your core.
-I'm not sure if you use Compact Fluorescent bulbs or not, but they won't work with x10 dimming switches. They do make a non-dimming switch (XPS3) that work great with CF's, but require a neutral wire at the switch. (I used this approach, and only use dimmers in my theatre room. Its worth the energy savings
-X10 is notorious for having a slow buss, so you can saturate the system if you do many things at once (I've only had this happen once while testing several dimmers at once). if this happens, everything will work but there will be a noticable delay.