Certainly could mill aluminum with proper endmills coated so you can run end mills dry.
Only in the center of the bed though as you move out the bed is too flexible. I have a poorly made base it took a 0.020 aluminum shim between the base and MDF and it is reasonably flat now. I think milling the MDF to get closer to perfection would work well. I have cut 15 parts cut positioned dead center on the base 7" x 2" Black Walnut mostly, and the stability and repeatability is excellent, definitely can’t take big cuts but the machine is very repeatable and accurate within its limits. It is hard to tell the cuts were not done on a mill. The fact there is nearly no backlash is a excellent feature of the A350. I think the aluminum base is a bit flimsy for the machine size though, A350. If someone made a kit to replace the base with a heavy duty version of the base and spread the Y AXIS apart the rigidity of the machine would be awesome and with a more powerful spindle would be able to tackle aluminum. Probably should have some covers to keep the axis insides safe from swarf. This would make the machine very rigid for the size of the large work area. Also throw out your warranty.