I've only recently started getting the hang of the full source build environment, so take my suggestions with a grain of salt. One of my main issues was that I work from home and can't have my main network tied up or torn down when re-installing or rebooting LMCE. I also wanted to reduce the craziness of my network cabling scheme.
After much frustration, I finally decided to virtualize the LMCE core machine. I already had an internal test server with VirtualBox and can now use it to keep "snapshots" of my system at certain configuration points. Also, this lets me run a separate VM running just the build environment in parallel.
I use VirtualBox on an Ubuntu Server 9.04 machine with 2 NICs. One points towards the always working network (cable modem) and the other points towards my LMCE test network -- both have WiFi routers. My server, LMCE VM, and builder VM all straddle both NICs using bridged interfaces (so they all get their own "true" MACs and IPs). To help out, I set up VBox to run headless and can start and stop each one using init scripts. Logging in is easy over SSH and even using RDP to peek at the screens!
So far, I haven't had any trouble using N800s, Media Directors (1080p), my HDHomeRun, Squeezecenter, and even USB devices (ZWave, DIO boards, and RS-232 for GSD).
I know this isn't for everyone but it might ease the pains of dedicating separate machines to test, run, and build LMCE. Until I get everything sorted out it keeps media management between rebuilds a little easier, too (music and DVDs stay shared on the server for LMCE to "find" on each re-install).
Finally, I followed the same "Building 8.10 from Source" Wiki article to set the builder VM up... very helpful! You might want to also refer to this post from Thom (http://forum.linuxmce.org/index.php?topic=7462.msg55175#msg55175
) for additional help on an effective build process.