ORIGINAL: Darto501
Not getting a quick answer, I took the long time for a second install.
Both installations run fine and completely independently.
The second one (unpatched) flies quite a bit easier than the patched version and easier than real life models it seems to me.
The patched version 1.9 (including heli patch) flies much more difficult and in fact seems harder to fly than real models.
Nice to have both versions instantly available for using either one as the mood strikes.
Maybe I'll have 3 installed on the same computer after I get the addon hangar pack!
EDIT: Observations based on flying helicopters only, no planes.
Right, you can install multiple times in different folders to have more than one working copy of FSOne. You are right that the heli's changed w/ the patches (some patches), but airplanes did not change. I will add that you do need the barebones first patch.
BTW - The new version (in the works) is currently installing in 15 mins, which is a vast improvement over the HH version where it's 45 mins on the same machine.