I don't see a forge/rats strategy working fast enough. Honestly, I think rats will go untouched in 95% of games. It's all or nothing with rats. There has to be a card that works well with rats to warrant its purchase. And frankly, not many cards seem to work well with rats.
So far, my favorite strategy is upgrade + rats. Buy an upgrade and a rats. Eat through your entire deck with the rats, and use the upgrade to upgrade the rats into more upgrades. Deplete the upgrade supply, deplete the rat supply, and then upgrade the rats into duchys. Or, alternatively, you can upgrade all of your upgrades into golds and then purchase out the duchy or provinces.
And even if it doesn't work, the absolute chaos of it all makes it worth it. Plus, imagine all that shame you'll impose upon your opponent when you beat them with rats...