The XMT is an awesome machine but it wont do AC Tig for aluminum. I believe the XMT is a great machine, I've used it on stick only but the other machines in the same catagory all work very well. I've used the ALT in DC tig and mig as have I used the invision in stick and mig and all perform well. Solid equipment and a good choice.
Good luck, with the venture.
pjseaman