I'm planning to try out R11, but...

[Simone Lombardo]

...if I already have R10, what will happen to the soundbanks and Appdata/Program Files folders? Will all data be completely reinstalled during the installation or removed if I uninstall it?

[FlowerSoldier]

Negative. It creates new folders. You can keep the old versions of Reason, I don't see why you need to uninstall 10 unless you need disk space. I still have 7 eight & 9 on my computer. I run 10.

[EnochLight]

...if I already have R10, what will happen to the soundbanks and Appdata/Program Files folders? Will all data be completely reinstalled during the installation or removed if I uninstall it?

Leave R10 alone, and just install the R11 trial - it shares your Preferences file and things should look/work the same as R10, but just with the new R11 features. That said, if you install the R11 Suite trial, that's a whole other ballgame. It gets its own Preferences file.

[Oquasec]

nah the reason versions dont mess with eachother on the authorizer.