Hi Wheelieman,
I brought my FE 550, last year, at the time, I was considering the CRF450, and the KTM 450 / 525EXC, and Husky 450/510, basically when I considerd what I got for my dollar the Berg came out really good - the Husky was really impressive too, but the berg had some good reports and reviews through 2005, with the exception of the old beef about how wide the tank is (but it really isnt noticable unless you are layin' it flat in turns).
There is bugger all to spent on aftermarket parts for the Berg, like bashplate and some proper handguards - the exhaust is well and truly competent, so considering what you'd want to add to say a CRF 450X, and with the runout deals that are sometimes available the Berg was it.
It probably comes down to how into maintainence you are, if you hate doing the periodic maintainance that all the high end 4strokes need, well the XR650 is a good choice, but its a bus compared with a berg.
If thats no problems, the 650 will likely exceed your expectations - take a read of the September 07 ADB magazine - poor comparison, but highlights the brute power of the machine - no other 500cc+ machine is close, total package is a pretty serious bike.
Azza.