When I first started IL2 after installing 10 I saw that my Saitek controllers weren't functioning as usual because the IDs on the HOTAS controls had been changed, nothing else, HOTAS only. I went into the game settings for controls and reassigned them. I had to do this twice and they have stayed assigned ever since. I have had a strict USB plugin sequence for years for the game and I stick to that...I have no problems now. I have a strict sequence because I have two Saitek lever quadrants and unless I plug them in and profile them in order my controls are swapped.
The only issue 10 has given my PC after installing, although it is a very small one, is USB IDs. All I had to do was unplug the hardware and put them back in the same USB slot. 10 recognised everything and updated drivers itself, although no new drivers were needed for anything Saitek. I was running 7.1 before so I was pretty much up to date.