I have not used it with TM13 yet, (I've just got one). I use it with the mini-timer to control the entrance hall lights. I also have it linked to the original hard-wired two-way switches, so I can control it from both ends of the entrace hall - it's totally transparent in that mode.

It was very easy to install and program using the mini-timer.

Here's the manual

[Link: letsautomate.com]