Hi Ish,
I am runnign Windows 10 right now, and that I am going to tell you a few things before you get started with your upgrade before you end up like me having to restore two PC's in one day because it didn't work correctly. Before you put Win10 on it, you need to make sure all drivers for GPU and Audio devices are up-to date and work with Win10. Then you need to install the latest updates for either Win 8.1 or Win7 depending upon the one you're running. I mean you need to install all updates including the optional ones. Once you do this, you need to have Windows run a check to make sure you're PC can run Win10. If it says it is okay, then you're ready to start. DO NOT RUN THE CHECK UNTIL AFTER THINGS ARE UPDATED, IT MAY TELL YOU THAT YOU CAN STILL INSTALL WIN10, BUT IT WILL NOT WORK! (I am victim of that)......
Now on to the other stuff, Trainz 12 and TANE both work with Win10. I can also confirm that steam works with Win10 and many of the games that steam runs will also work on 10. I am not sure what other programs you are using, but some deeper reasearch will tell if you they run with Win 10 or not.
I'm not quite sold the stability of it just quite yet. They're are some areas where I have noticed that there are visible bugs that cause lock-ups and crashes. I'm holding on though, because it is new and the next update coming this month may fix it.
Performance is better. I have noticed a boost of FPS in several of the games I play,even with sliders set to super-high detail. This is something that I did not notice with Win 8.1, making it another reason for me holding on right now.
Hope that gives you some detail!