I agree with the comments about giving contributing members higher rep power.
Since most rep is given out for maps, a combination of number of posts and rep received is a good way to balance the two types of forum contributions.

I was questioning the rep for membership time value because some people disappear for years and then reappear. (I was totally absent for 7 years.)
But there's no way to monitor that and it really isn't that many rep power points.

I agree with Korash about a lower starting value in the 1-5 range.