Newer version is actually safer than the old one, and the new version blocked like 70% of the mods/cheats you can find online, because they don't work well with new version, plus cheater dont update to R4/R5 anyway
The latest and official version is more safer and better in my opinion
Correct, but 0.3dl is the newest version. It was released in 2018 or 2020, I don't remember. While 0.3.7 branch stopped being updated in 2016. The thing is that Kalkor just deleted 0.3dl from his website for unknown reason.
0.3dl introduced a new feature that allowed server owners to include new models of vehicles/skins/guns in their servers. While I don't suggest to code any of these for MCNR, there is no reason to limit access to the server for clients with 0.3dl version, unless Mike knows something that I don't.