i recently sold my 1997 540iA, which i only owned for about 4 months. I have been driving Bimmers for 25 years. i also ride motorcycles and have presently a Honda VFR800 motorcycle. I have owned various motorcycles, including BMWs, and the VFR800 is the best overall bike I have ever owned. i am very attentive to the handling, weight and "feel" of cars and morotcycles.
HERE ARE MY THOUGHTS ABOUT MY NEW 528: the 528i is a much better car, in my opinion, than the 540, for two fundamental reasons. the extra 400+ pounds for the 540 fall virtually all on the front end of the car. thus, the 540 feels much too heavy to me, and almost feels like a front wheel drive car. i feel like i am being pulled by the front wheels of the 540, rather than pushed by the rear wheels of the 528.
second, the rack & pinion steering in the 528 has a much better feel. i can feel the contact of the front tires on the road with the 528; i always felt detached from the road with the 540.
sure, the 540 is faster. but, the 528 has a sportier and fuller character; a fine degree of refined rawness.
this is just my view.