I say it's worth it. I had a set and it really lowered my cruising rpm's. Seemed like it would hit the powerband a bit more. But then again, it was a real proma. So much better than the copy!
Here are more pics, (might have the tooth count wrong)
Gearing on this one is the same, if I remember correctly:
It would be nice if somone with some hobbing knowledge could churn some out with different ratios.