Hi there Mark,
Back-up your user patches and then install over the previous version. That should work ok.
In saying all that, I personally tend to, unless if specified not to, back-up my patches, uninstall the prev. version and install the new version and the expansions from scratch (not that I own expansion, not for gladiator in anyway
).That way you're sure nothing will go amiss, and really, the Glad2 installs are small enough that it won't take forever to do