Not too many modifications were required to install the new ASUS board (click here for more details) The only real issue was the secondary power supply's heatsink being in the way of the front panel connections. A quick snip with a pair of brake cutters fixed that up.
Here is what it looks like now:
The RAM shown in this image is "loaner" for now since they ordered the wrong parts.
Overall it is pretty clean. Not too fond of the location ASUS chose for the ATX connecter, though.
For those that are interested, I took some dB readings of the fans today at 1 meter (about how far I normally sit from the machine).
With only the "normal fans" on (i.e. none of the switches enabled) I'm reading 62.5dB on the C-Scale. With all the fans on that reading jumps to 71.5 dB.
So, yeah - it is kinda loud