If I understood the various FwM and balance documentation lying round about Aimed Shot, then the new mechanic will work like this:
Aimed Shot = instant if (self (concealed) && target cannot see you)
Agents get a lesser instant aimed shot if not concealed.
Anyone else gets a cast-time aimed shot if not concealed.
A question about the last point - is the cast-time aimed shot useable in PVM? Will it interrupt normal shots if so (or to ask a question, will it be worthwhile to consider using aimed shot in PVM)?