Nomad
You may be able to answer that better than me. My guess is that it is jurisdiction-dependent. The very nature of Cat B means that there are no performance guarantees but whilst it would be normal to have a minimum spec for Cat B as expressed in the PA charts at 100% some jurisdictions may turn a blind eye to Cat B operations with a below-spec engine. There are many places around the world where there are very few if any performance requirements and if the thing starts and runs then it's fit for purpose.
Of course if you were the LAE signing for it you may have a different view but then that would be a company decision.
Back in the days when the wood smoke in Borneo clogged up the CT58's in Brunei-Shell's S61's they were changing engines on a monthly basis but in the meantime, despite introducing hot washes they worked out a way of doing a PA check and then reducing the max take off weight depending on how far below spec the engines were. You can see where I am coming from I guess. In some parts of the world a flexible approach to PA checks and PASS/FAIL can be arranged.
OUTWEST - I don't believe that translates into a practical difference save that Cat A must be done before take off and Cat B can be in flight (hover). You can't (normally) do a PA check on a commercial flight with pax or cargo aboard so you would have to make a special flight if you didn't do it in the hover.
G