Well I used to use that plugin and OH MY GOD THAT PLUGIN WAS HORRIBLE! I wanted to remove it but there wasn't a good equavilent for it. Then I discovered Comment Notifier. I immediately removed S2C (which was also painful to scrub every dirt of it from my database) and installed it. It has a long way but it surely is lighter than S2C.

You lost me Mark :) Although, I would be willing to test your plugin if you have a converter from Comment Notifier to your new plugin. I have around 200 subscriptions.