One of the advantages of surgery is that the whole prostrate is available for testing. Biopsy only samples a very small portion of the prostate and can miss more aggressive sections. And it can tell if the PC has moved into the margins of the prostrate (more likely that it will spread).
And with the 5 for the secondary Gleason and relatively high PSA that would be my choice. Then the post surgery pathology reports indicates the need maybe followup with HT and RT.
Sloan Kettering has some monographs on the outcomes of different PC treatments.