When i was looking for an E34 I rejected the call of the V-8's because of how full the engine bay seemed and other issues I had read about, plus I like a strait six. So, I ended up with a 1995 525i M50 5 speed. That was a four years back and i have learned that while no 13 year old car is problem free but i have only had a few unpleasant surprises, like the ingnition lock transfer bar failure (600 USD) and the front end bushings (another 600) which I thought might have a few good years left. The rest of the stuff has been normal maintenance and these are exceedingly well built automobiles and IMHO I agree are a pleasure to drive. That said, what kind of 525i M50's do you really think are left out there, the maintenance deffered cars have the potential to bury you $$$$-wise, I would stick with your 530 which you know and unless the perfect 525i presents itself try to learn as much as you can about preventive maintenance and go with the flow,
my 0.02 USD,
BR,
John
1995 525i 5 speed 106,000 miles and hopfully many more