The Death of Post Counts

Many times, many places, the removal of post counts has been touted as a great solution to useless spam on forums. But with the removal of post count comes issues such as how newbies know the regulars from from the occational visitors and such. I propose that we hide postcounts and replace them with an activity metric such as the following:

Where
vw=the number of days in the past week that the user has been logged on
pw=the number of posts the user has made in the past week with a max of 4 per day

vm=the number of days in the past 28 days that the user has been logged on
pm=the number of posts the user has made in the past 28 days with a max of 4 per day

activity metric= (vw*3+pw*2)*2+(vm*3+pm*2)

In this case, the maximum points would be 462 (maximums are good, less incentive for spamming).
If a user were to visit every day but not post, he would have 126 points, or 29%.
If a user were to visit every day and make one post each day, he would have 210 points, or 45%
If a user has not yet visited for the day, it represents 5% of their total possible points.
If a user is inactive for a week, it will result in a point reduction of 50%.

I'm interested in thoughts on this idea, as well as alternate methods of calculating activity metric, reasons why this would or wouldn't be good. I am NOT interested in one or two word responses such as "yes" "no" "fuck you" "this sucks" "awesome", etc.