I'm a TD-3 convert too. In addition to its other virtues, TD-3 is hard to screw up, compared to Technidol, which is pretty touchy. Also, Technidol gives a very abrupt shoulder; TD-3 gives a shoulder that goes on forever.

As a staining developer, TD-3 works a little better in an alkaline fix like TF-4, but looks fin ordinary fix too.

The only downside is for the chemically fearful: it is pyrocatechin-based. As long as you're not tray processing with bare hands it's not that big a deal.