Given the capacity of the STW, the Fed 215s are right in line. If you have a load developed with another primer, then yes, you will want to step it down a bit and work back up as pressures allow. You should be doing this whenever you change a component, so it's just a good habit to get into.
I have data with both the powders you cited here, and would be more than happy to pass these tables on to you. Just drop me a line at firstname.lastname@example.org
and I;ll get those off to you.