The difference between the MXC and EXC in in the gearing. The EXC has a wide ratio tranny so it may have a lower first (not sure) and it has a taller top gear to go faster. The EXC also has lights included.
The Husky is definitely more suited towards the woods than desert. The WR is great in the low end and mid range and does have some on top as well thanks to a new pipe for 02. for tests on the WR 360 go to:
Husqvarna Australia
and
Husqvarna USA Scroll down on this page.
Look for the tests.
Any of these bikes are great. My friend rides an EXC and wins enduros on it. Myself, I am a bigtime WR360 fan and am impressed by Husky's 13 World Enduro titles for 2001 and 2002.
Just choose you cannot lose with these choices.