Talking entirely thoretically here (as I will never achieve the levels of development and power * that John and Fen have), I have always looked at things like those Stack displays with a slight cynicism. Yes, they look fine, but when you are devoting as much concentration to what is going on around you (namely, looking out of the windows), instruments need to be as big and clear as possible. And those rev counters are not exactly huge - smaller than the standard affair in the 944. And the digi numerals are distinctly hard to read.
I also have a preference for gauges over digi displays. Gauges give a qualatitive feel, namely a very quick glance gives you quite a good idea of what is going on. Numbers on a digi display don't have this property - you need to look at them and mentally process them to tell that 1- 2 - 7 on the MPH display is pretty brisk ...
I suppose the argument is that if you are on the track then the revcounter is the most important one, and that has a dial, and the rest (speed, temperature, fuel level, oil pressure etc) can all be fitted with alarms to warn you if they get to worrying levels. Maybe I'm just stuck in road-car mentality. Still can't see a good argument to change tho'.
Oli.
* - The fact that S2's are much more powerful, suffer no lag and are driven by much better looking people notwithstanding, that is ...