640 v 525
My 02 640 now has over 45,000k on it and I've had no problems......touch wood. I've had an 03 525 and a 05 525. I got rid of both before I put too many k's on them and had valve probelms. Both had about 10,oook on them and the valves were getting a little bit tighter each service even when I changed the oil and filters every 500k .
I think you would be very brave turning the 525 into a tourer and expecting to get decent k's out of a high performnace engine. also if you plan on loading it up with touring gear you may also need to look at reinforcing the rear subframe to take your panniers/saddle bags/sleeping bag/thermarest/clothes/food etc.
steering damper is highly recommended. I have only just put one on my 200 EXC and it totally changed the stability of the bike.
stick with the 640 as an adventure mount and have a look around for a cheap bike for the tight stuff...
2012 KTM 250 EXC-E
2006 KTM 950 Super Enduro
2002 KTM 640 Adventure
2001 KTM 400 EXC Motard
1989 U1700 Unimog Doka-The ultimate support vehicle