I understand that AI routines and commands are being reworked for version 5.0. I think AI is a very big project to address and TFS wanted to get the most fixes out in a patch as could be done in a reasonably short time. All for free if you already have Cliffs of Dover, very cheap through Steam if you just want to try it out.
Slip, there are other good reasons for downloading 4.5, including some new sub-versions of aircraft types, flyable Beaufighter, DX11 support, 64bit .exe, fix of altitude bug (very important if you fly blue), many corrections to FM and damage model, etc.
If you are flying offline, you can still have more than one version of the game installed. If you are worried about keeping them separate from each other, copy you old version to a thumb drive and run it from there.
Last edited by Murph; 11/29/17 05:09 PM.