brande:
You are correct but that is an above average welders ability to do it well, where AC is relatively easy by comparison. I have tried it and it really kicked my butt and I wouldn't even think of doing it as a for pay job since my skill isn't that good!!!
Peace,
pjs
The other thing about it to remember is that with no EP, there will be no cleaning action on the arc. DCSP for Aluminum requires much cleaner material.
For example, there will be times when only AC might do the job, such as a cast motor housing that has seen lots of oil on the other side.