Just my $.02
For what it's worth, I've ridden my DRZ, on average, once or twice a week for the last ten months just about as hard as I can. MX and woods. I've modified it, tweaked on it, maintained it well and just generally used the heck out of it. I have had no probs other than a leaking fork seal last summer, and that was covered under warranty, believe it or not. I haven't ridden an XR400 but I imagine that in stock form it is a little more tame. The DRZ is very ergonomically efficient, IMO, feeling much lighter and more nimble than its weight would indicate, with smooth, sneaky-fast power! Hope this helps.:)
BTW-I got it at the local Honda/Suzuki dealer. Wouldn't that make it easy for ya?! ;)