Further to the original question -- my first BMW was an e39 540 sport 6 speed. When this car was designed, it was intended to be the successor to the e34 M5; BMW quickly designed the e39 M5 in response to an AMG offering with more power. I've upgraded the brakes, suspension, steering, changed the engine mapping and installed an lsd with different gearing.
While the S62 will rev higher than the M62, on most roads in the US, and even on a shorter more technical track, it is difficult to use that extra kick. On the autobahn, or at VIR, the e39 M5 would be substantially better than a 540.
I agree with Chris that the e39s don't have quite the feel of the e28s (or the e34s). I think this is primarily down to the need to use recirculating ball steering for underhood packaging and the added weight of the e39s. I tend to prefer heavier cars, which is why I went for this one.
Peter -- If you happen to be in the neighborhood sometime, you are welcome to drive mine.