I really really like this script! One thing to consider would be to add TRIM TO MARKERS. I probably would start using markers in layers that dont have keyframes for a reason or another in the in/out point. Even without this kind of feature this is really great script! Thanks!
Trim Matte to Layers (inverted from what it currently is). Often times when I create a matte, it's not trimmed to the layer it's matting. I've never needed to trim a Layer to the Matte since the Matte usually comes second.
This one might be a stretch, but if it's possible to Trim Layer to Comp Boundaries. When the layer moves offscreen and is no longer needed, that would be a great place to trim too.