7-Zip: Question

I want to use the "associate with" option in 7zip on my own computer, but obviously since that would require having to write stuff to the registry it wouldn't work properly if I'm running 7zFM.exe under the portable launcher. But if I didn't use 7zipPortable.exe and ran 7zFM.exe by itself, would this option work properly? Basically, what's in the 7zipPortable\App directory is a compressed version of what I would find in the "C:\Program Files\7zip" had I installed 7zip, correct? So is there any reason why this wouldn't work?