Linux Mint Xfce isn't based on Xubuntu but on Ubuntu, so you might give it a try anyway. But there is nothing wrong with continuing to use the LTS, that is what it is for after all
I like Linux Mint Maya Xfce so much I plan to stick with it. I'd even install it on my htpc if I dared, but my htpc already has Xubuntu 12.10 and the thought of doing all the configuring and customization I prefer is daunting. Xubuntu 12.10 works okay, but I get a crash report about once every three boots or so. Annoying. I realize Linux Mint Nadia Xfce won't be based upon Xubuntu, but Ubuntu, but I don't really know what is causing the crash ultimately, so am a bit leery of the 12.10 codebase, which is supposed to be beta-ish after all ("Quantal" not being a LTS, but an aggressive step towards the next LTS). My plan at present is to wait 'til Linux Mint releases its next LTS, at which point I'll face the decision of going with Cinnamon, Mate (possibly it will be around then? I don't know), or Xfce.
For my htpc, I don't know. If Xubuntu continues to aggravate with the random crash reports, then I may decide it's worth the trouble of replacing it with LM. (Never going back to straight *buntu in this lifetime, Linux Mint all the way.)
If Linux Mint ever decides to stray from the Ubuntu codebase, I'm not sure that would be such a big deal. Might even be a good thing, but I don't know. I must confess curiosity about LMDE. I only use a handful of applications: Mozilla Firefox, Mozilla Thunderbird, Gimp (maybe?), and Dungeon Crawl Stone Soup. I think all of that is available in Deb. I'm getting ready to look at K3b as a DVD burner, but haven't settled on one yet. I plan to use LibreOffice most likely for word processing. Other than that, Filezilla for ftp, and I can't think of any other apps. I just want the OS to look nice and handle file copying and editing with ease and offer certain conveniences and customization utilities. I don't understand why Ubuntu spent all their developer dollar on Unity when the users wanted something else. You know, the users are always right.
Hm. I did have too much egg nog this evening. Wrote more than I expected.