I'd like to suggest it's worth stating somewhere how to switch between UFO to TFTD, or better, changing it to something more intuitive.
Issues with the current system:
* It doesn't follow standard UI precepts. When I changed it to TFTD on the mods page and it changes the mods that are available, I expect this is only saying "these are the mods that should be enabled while you play TFTD". I very definitely don't expect it to also mean "This is also enabling TFTD".
* If I - as someone who's been using computers for as long as XCOM has been around - struggle with this, it follows other users with less computing experience may as well.
The way I expected to do it was on the new-game dialog. Exact same drop-down is fine, just a copy of it there.