I know all about WinRAR and how to make very complex SFX archives with it, I've been using it what seems like forever now.
I tested 3.93 against 4 final & it seems that 3.93 max compression is (just slightly) better than 4, or at least on files I tested.
4 also removes windows 98/ME/NT support & raises it to minimum win 2000 or higher.
For now, I am using 3.93 due to the (slightly) higher compression!
For now, I am using 3.93 due to the (slightly) higher compression!
If you're after the smallest size archive make sure solid compression is enabled, but also understand the caveats of enabling it - you won't be able to extract/recover anything past the corruption point in an archive with solid compression.
I didn't notice the compression differences between 3.93 and 4.0, but then again I really wouldn't since I use a recovery record the minimum being 3%, and for really important stuff 10% (which is overkill) and no solid compression.