Some DA's can be locked so it just spins instead of wobbles. It essentially becomes a grinder and shouldnt be used on sheet metal. It will strip paint in a hurry but also can chew into the metal quickly.
The SCT is made mostly for stripping metal and prepping for body work. If you want a really good DA, check out Hutchins. Expensive but in my opinion well worth the investment.
I use a locked in DA with 80 grit to strip almost everything. You have to move around to keep the heat down and be careful around body lines . In tight spots I use a 2 inch brown Roloc disc on a angle grinder.
