I've been running both TS12 and T:ANE on the preview of Windows 10. The current build, along with the latest drivers from NVidia that came out yesterday has proven to be the most stable. Overall, the performance with Windows 10 is much, much better than previous versions of Windows including both Windows 7 and Windows 8.1. Having said this, W10 should run both TS2009 and TS2010 without issues if you can run both of these versions in Windows 7 or 8.x, they should run fine in Windows 10. Just follow the usual install and run as Administrator just as you would with other versions of Windows, as these are older versions of Trainz which need that.
I recommend upgrading as this has proven to be a good operating system. That said, I highly recommend backing up your data prior to upgrading. This is a recommended practice anyway no matter what operating system you have, whether it's Windows or not. Having a good data back up means that nothing will go wrong, and is a good thing to have anyway. Always remember that data can't be replaced but programs usually can.
John