I looked at the refuge x. That is a crazy weight for two! Who has used that thing?
Only Ron Moak at this point. I ordered one and it is supposed to ship in early May. I think the main concern is that is may be a bit cozy for two (I actually got it as a one-man tent). Of course, the Montbell tent has a pretty small floor area as well.
In general though, if you really like to use a tarp, then I would encourage you to do so. You can probably rent another bivy and maybe a bigger tarp as well (if your existing tarp isn't big enough). Who knows, she may really like that too.
If you go the tent route, then I definitely recommend a tarp tent. You have almost all the advantages of a regular tent, without nearly as much weight. You sometimes have to handle condensation or wind properly, but that is (in my opinion) a small price to pay. My wife came from a standard tent background and is not nearly the gram counter that I am, but would not want to go back to a double walled tent (that exists as of this writing).