Jeff-
My oil gauge works properly, and it appears my fuel gauge is accurate now after a re-set. I'll confirm once it gets low after I deal with replacing my clutch
The oil level gauges are different on the Turbo motors, but should be the same on a C2 or C4. As I said, mine is accurate. As for fuel, a C4 or TT gauge will not be accuate, due to the saddle tank to accomodate the front drive components.
As far as this being "worth it," mine has gone fairly smoothly, and I am very happy to have oil pressure, voltage is semi useful (useful to me as I have a high end audio install), and I love the dot matrix cluster and was thrilled to get rid of the "pretty Boxster" font on the gauge faces.
You could certainly get the same information by doing a gauge pod, and before I did this I was planning to install 3 gauges on top of my climate controls where the cubby is. I still would like oil temp somewhere, but I am very happy with this upgrade. Worst case, I'll get the dealer to calibrate my fuel level sender if it is still off.
Patrick