The issue with "split archives" is one I have come across in my time as well. The only real way around it is to just say no to splits.
The majority of people I know use WinRAR to compress files, WinRAR allows you to create both ZIP and RAR files. RAR allows for greater compression in my experience.
Personally, I have no preferrence as to whether RAR should be allowed. If it makes it easier for people post with RARs then it's a good idea I suppose.
Count me in as well.
