This is purely an informational thread.
Let me preface this by saying that neither Steve or I am responsible for any shagged saves if you attempt this. Be especially mindful that your bug reports from this type of game will be unreliable at best.
As you should know the 1.4 patch is not-save compatible however I am an idiot and decided to try only updating Aurora.exe - omitting the 1.4 Aurora.db.
The results weren't as catastrophic as you might imagine. The only problems I noticed were that some events lost their background colouring that I had assigned and any order templates I had made vanished. Everything else was fine and remained fine for approx 5 in game years of me mashing 30 day turns. In my save I had my own freighters and civilians milling about between systems, ships and installations being built as well as research. Designing missiles was also fine so I assumed that designers weren't broken. No combat was taking place.
Saving and loading saves also seems to work fine.
I specifically checked if the ECM/radiation bug was fixed now and it was, like it should have been - so at best doing this will give you access to non-DB related bugfixes.
I cannot stress this enough that my testing was by no means exhaustive and this could easily mess up your save later on and especially advise that you do not do this if you want to help Steve with reporting bugs.
Edit: I forgot to mention that I tested this only on a preexisting 1.3 save. I have not tried to see how new games behave.