My situation is not exactly like yours but I did have a bad margin as part of my post surgical history. The oncologist matterafactly just assumed I would start the radiation but my surgeon, who is also an oncologist, guided me toward watching the PSA every three months for the first year and begin radiation if it showed any sign of rise.
I asked the pathologist some more information about that margin like how long, how many margins and how many cancer cells could have existed in it..
Your initial .34 and 30 day subsequent .04 may be of significant value as you make your decision. Was it the same laboratory? Could it be that there was remaining cancer and it died off because the blood supply was cut off from the surgery?
I did not have extension like you but did have a 3+4. I know some Docs don't even take a PSA for a few months after surgery because of inaccurate readings.
I am not a Doc by no means and this information is just my opinion. But even if your PSA rises again you still need a few more months to heal before any other treatment could begin.
As far as the study goes I would have no problem with participating in it if it would help others, but I would not take any additional risks with experiments or treatments for your condition is treatable with proven methods.