Another difference is the frame. Both the Lawman and the Tactical SS have forged frames. I believe the Trojan is built on a cast frame. Nothing wrong with that, but forging is a more expensive process.
I recently had a employee from STI out for a CEH1 class and I fell in love with 1911's all over again...He brought a nice selection from STI out and everyone in the class had a chance to run a few of the STI's . I do believe he made a few sales, LOL!!