Thanks for your interest in the SC2, and for using the Forum!
6mm is a lot, and the thickest I found for acetate sheets on google was 3 mil, so I'm operating under the assumption that you mean 6 mil.
I wouldn't recommend the SC2 for cutting acetate. It's one of our value hobby cutters that are really more geared to cutting vinyl and easier stuff like that. It's possible that it may work with some fiddling, but we're not confident enough to recommend or support using an SC2 for that purpose.
For cutting acetate, we would recommend one of the Titan series cutters. Depending on how big you want the stencils to be, the Table Titan 1 can cut stencils up to 15" wide, and it's $549, which is only $100 more than the 28" SC2 at its base price.
A carrier sheet would be a must in any case, though, but it looks like you already know that.