To make it short, it’s amazing. Since SURBL looks at the hyperlinks embedded in spam-mail, it winds up being extremely effective. I installed SA 3.0 on it’s release day, and integrated it with my Messaging Server, just like I’d had 2.whatever setup. The difference was astonishing. I’d had to crank down the spam threshold to something like 3.8 in order to get a manageable inbox. Now, with SURBL goodness, I can have the spam threshold up higher at 7.0, because when an email comes in with a nasty link in it, it gets assigned a score of 10.0 automatically, and it’s therefore spam. (That’s how I have it setup.)
Result: false positives drastically reduced, and a smaller inbox. I’m a happy camper.