You need to elaborate on why you think “I’m not yet entirely certain that would be the best move for me “
Xtreme can do all that Weaver II could and more , and more easily, so I really don’t see any reason why you would think that.
I am not sure what you search for with the sniffer, but given the activity on this site I would say there must be quite a number of site using Xtreme, make sure you are looking for the right stuff, you can explore the Demo site (below in that thread) to make sure you know what to sniff for.
Weaver II is also end of life which means that sooner or later, you will need to switch to Xtreme.
There is a converter and a detailed procedure (in the xtreme tutorial section of this site) to convert a Weaver II site to Xtreme that makes the process relatively easy. If you did have a lot of Customization beyond the options, there may still be some work though, mostly to make sure you take advantage of the new features in Xtreme.
But knowing Weaver II, you will be at ease with the similar (is easier) interface of Xtreme, and you can take your time with the process.
You can create a test site in a sub folder or sub domain of one of your site, install Xtreme and have a look at all the sub themes.