Should only make much of a difference in track use situations. My M-Sport has 'em, and friend's M5 doesn't. Otherwise the brakes are the same between the two cars. I've never noticed any real difference for around town use. But I've not used either car in repeated heavy braking situations yet so I can't tell you how noticeable they are.
Since you appear to see the track once in a while I'd slap 'em on. And if you've got T-Stars it'd help those out even more with their cooling. Would hurt Turbines cooling performance though.
Cosmos Black/Black 1995 540iA M-Sport
BMW Individual Exclusive Edition, 1 of 65 total, 9/25/95 Build