I've finally made the switch from Pine to Mutt this past weekend. It was after upgrading to Pine 4.50.The new version had some issues, and rather than spend the time wating for another version, I decided it was time to finally bite the bullet and upgrade. I'm glad I did. Mutt is far and away more customizable than Pine, and it integrates with vim nicely. Plus I can read my e-mail much quicker. The only downside is the HTML mail processing is sub-par at best, but I don't really care much for HTML mail anyway. This configuration file helped ease the transition process a whole lot.
Also I've been using Spam Probe to filter my mail of SPAM. I barely even see SPAM nowadays unless I'm at work; it's that good. It took a while to get here, but all I have to do is save the SPAM in a folder, and forget about it. I have some nightly jobs which add the entries to the database. I don't think I've ever had a false positive yet. Highly recommended if you have a Linux/UNIX machine processing your mail. (And if you don't, you might want to think about building a machine to handle your mail anyway. Yes, it's that good. :) )