@ Jim - In that case, I would ask that any changes to V 3 be available as a single "scr" file download besides the complete "install" package you have now.
I know that an install package will add extra files to my system (but won't matter to anyone who already has the "Prolific" install) while a simple file replace will not mess anything up.
I believe that the installer must be used at least once (first), to get everything created correctly in the right places, for whatever version of Windows is being used. At least that would be the case for the "average user".
In the past, there have been instances where additional operations were required, because of changes in the executable/features/whatever. For instance, Beta 5 required an additional script to fix the registry. The point here is that "just replace the .scr file" might not always be the full procedure. The installer would take care of whatever is needed.
In my opinion, asking "average folks" to download a new .scr file and replace the one in system32 is asking a bit much. And, since January 26th (2009) when the Installer version became available for test - Beta 8k - I'm not aware that a bare .scr has been made available (on Serenescreen at least).
Finally, at least for SereneScreen, everybody who purchased MA3 has been promised that there will be updates.