I think you're doing the right thing, and thanks for the effort.  Too many times, a really useful and interesting thread ends up locked.  I'd rather have the derailing posts removed, including my own, than have useful threads locked.

I've never been a mod here, but I am at other sites, and I know it's not easy.  A large site like Slashdot needs community moderation, but a small one like this works best as a benevolent dictatorship.  Rules, warnings, etc. are like catnip to the wannabe Internet lawyers out there.  Some people live to skirt rules, try to turn mods against each other, and see how far they can get before the banhammer falls.  It's a huge time sink, and just not worth it.