Oh, I don't think I noticed that either. Anyway, I looked at both products and I think the one you have now saves the gender in a custom profile field that you created, right? And there doesn't seem to be any special uninstall code, so I think if you uninstall it you'll still have the profile field with the gender info.
The vb4 version I linked to doesn't have any product file to install, it is just some template changes. So I'm not sure if that will give you the same features that you have now. But in any case it also uses a profile field so you should be able to skip step one of the instructions.
The only other option I think would be to modify the vb3 version by updating the templates and the plugin code, but that would probably take someone with some coding knowledge.