While they can behave differently (mostly on non-Ubuntu systems), gksu and gksudo are not really separate topics. They're provided by the same package (gksu). They're even the same executable (which can behave differently depending on how it's invoked...but rarely on Ubuntu). Furthermore, the vast majority of questions asked about them don't have anything to do with any su vs. sudo distinction.
Therefore, I don't think it makes sense to have separate gksu and gksudo tags. While gksudo seems slightly preferred as a command and there are more questions tagged gksudo, I think the main tag should be gksu since that is also the package name. But I don't think it really matters which is the main tag. I do think we should:
- have both of them (no blacklisting)
- have one of them be a synonym of the other
I would suggest the synonym myself, but I don't have a high enough answer score in the gksu tag. Furthermore, I think the community should decide which should be the main tag.
gksuas the main tag