lapieuvre
All I can say is that you are looking for problems! My 2 cents is : if all your softwares work on win 7 why upgrade to 8? Chances are bigger your softwares won't all work under 8. Good luck!
To date I haven't found a program that wont work in Windows 8. I am not sure why this is being proposed by some members. Certainly Sonar will. We know this because I and many others have been running it just fine. Also if anything one may find fewer problems under Windows than with Windows 7. Its more advanced. Than there are those that seem to propose plugins wont work in windows 8. So far I have not seen this or read anything to suggest that this notion is true. All my plugins that I installed for X2 on Windows 8 run fine.
If you are using programs that were released for win 98 you may find they wont work but there is most likely a newer version that will.
Generally if it works in Windows 7 it should work in Windows 8. I know that the programs that I used in Vista 64 bit also work in Windows 8 64 bit. At least all the ones I wanted to work.
Full disclosure, I haven't tested all windows programs on win 8. I doubt anyone else has either.
Really there is no reason not to go for Windows 8 as it is the current OS and is a better OS.
When one gets use to it its hard to even want to go back to an older OS. You gain a great deal and loose nothing.