OK. I made it to the hotel and have a nigh tot kill before the flight home tomorrow so I am here to answer what I can as best I can. I guess to answer your question better I would have a few of my own first. What size X Carve are you thinking of getting? What type of things aside from aluminum do you plan to mill?? Are you wanting to run it daily on aluminum milling or from time to time. say maybe a day or two a week?
In a short answer and without the above answered… Yes and No… The X Carve CAN mill aluminum if the right spindle is used (Dewalt or a VFD .8KW or so) and the right DOC and feedrates are used. It is not a fast process as say maybe a plasma cutting or such might be for cutting. The 2" size would be at the outer limit of the X carve for milling and would depend on the mill size (500X500 or 1000X1000). Your toolpaths would have to be very carefully considered on a job of that thickness also.
Cost wise the X Carve is a good deal, but would need an upgraded spindle and at least a TinyG controller or the new X Controller (once it is released) or maybe a http://www.planet-cnc.com/index.php?page=home controller. the stock controller just would not do well for that level of milling. A really good CAM software is also needed but I am guessing you have that already for your other CNCs.
So my gutt feeling based on what I have been doing is this. The X Carve could be used in the fashion you are asking about. But it would be pushing it to the outer limits of uses I think. If you allow enough time and use a good spindle, your DOCs would still be at most, 3/4MM and I would say closer to 1/2MM or so. Even then your feedrates would have to be low and the jobs would stretch into the 15+ hour range is not into the multi day range for a large 2" project
On the larger sized mill I would say it is a no go over all due to flexing issues on the longer sized makerslide. The smaller mill has much reduced flex, but then things like belt stretch come into play if you drive the spindle too hard which will then ruin the job overall on such a thick stock.
So that being said what would be your options…
If you are on budget and have time for the jobs you mention. I think the smaller X Carve could mill the jobs with a good .8KW spindle and upgraded controller. But then the question becomes if you have the time needed to allow the mill to take the shallower DOC passes it would need to not induce belt stretch. If you can afford the needed time for each job, then I think it would work for you.
If the budget can grow a bit and you need the jobs faster, then I would go with a larger format mill. The larger mills are stiffer and can take much deeper DOC and at much higher feedrates. A dual ballscrew gantry mill will far out perform a belt driven mill and allow for the deeper cuts and faster feedrates. But with that comes a higher budget costs of course. Not through the sky high, but in the order of 2 or so of the larger X Carves decked out nicely. But the increased production should offset the higher upfront costs and in the end I think you would have fewer issues with the mill for that size of stock.
The X Carve is a good little mill and does a great job on things like wood, plastics, FR4 and thinner metals. But when you start to push into aluminum and such above 1/4" is where things start to need more care and issues tend to come up.
I am heading home for a few days between shoots so I will be around far more if you have more questions or if any of the above info about your projects would change any of my answers above I would be very happy to try and answer anything else that might come up on the subject.