I think you are right to consider your position in the light of upgraded findings. In your position, I would seek an opinion from another Urologist of good standing who would need to review your histology, scans and tests to check whether he/she agrees with the opinion of your present one. This may help you decide if the risk of continuing with AS is small enough for you to continue with it, at least for some time. Another consideration is that whilst you might well cope well with RP now, this might prove an increasing challenge in another year or more. Certainly, you wouldn't want to delay treatment until the cancer had broken out of your Prostate.
Do let us know how you proceed and get on.