When I wanted to switch from my Ninja to a KLR, I've read a lot there...
http://www.klr650.net/forums/
It's like the ninjette.org of the KLX, very friendly and courteous. Tons of tips, advices, etc...
From what I remember, try to get a later "newgen" KLR, 2010 and up, the doohikcey was more reliable, but the spring remain the same tensionless piece of metal. And they're less oil burning story too, but if your ride at highway peed constantly, what the oil level every two fill ups, the high RPM make the engine burn more oil.
Try to get one that has the doohickey done as well as the spring. If it has the Thermo-Bob conversion is a big plus. The bob thing is to keep the coolant température more consistant with less variation, which should help with the life of the engine.
For the rest, you'll be able to customize it, like the Ninja even more...
There you go...