Great topic! As Zinz mentioned, I have an 123 as well. Why not share my experience with it?
I bought mine in august, and installed the 123 with a curve from another 02 enthousiast (posted by Zinz a couple of posts earlier). Never changed much about it as the car was going great with this setting and no static advance. Dyno resulted in 90hp with a stock 1600 motor with dual Solex carbs, everything ajusted as it should. Not bad at all so I wasn't triggered to change much.
When Zinz asked about my experiences with the 123 we started brainstorming about things to try out, just by talking about the settings we had, and things we might have to try out. Since then my car has improved quite a bit. To keep the long story short, static advance is now at 10°, but I retarded the curve by 2-3° above 4000rpm as the car was running hot when I kept driving at approx 5000-5500rpm in fourth gear (did that on a safe, wide, straight, empty road for testing purposes only, of course).
I tested the curve and static advance settings (and a lot of others as well) with the tuning tool included in the 123 software. I always used the same piece of road and did multiple measurements in both directions with the same settings, and then took the average (pretty scientific right?). I haven't put the car on the dyno since then, but I really feel the car is driving at its best now, compared with before the 123, well, it's a whole different car actually! If there's anyone doubting about an 123 out there, just order the thing right now!