New system seems to be working great. The new question, complete with mathematical misdirection, even threw me at first (for not reading the entire question).
A few of the more determined and virulent spammers have come back recently, the ones that were still managing to create 50 posts or more before being blocked. This time, they managed between 3 and 8 posts. :) I'm glad that the 1 post/minute limit is working, and even more grateful that everyone here is so proactive about spam control. Many thanks to all of our sharpshooters!
Here's a huge "THANKS" to Mr. Admin for the implementation of the spam-reduction system.