I don't run high test doses right now, and haven't for a while, so anything above 25mg/day proviron tends to drop my shbg too low relative to my T and E levels and screws up my sex drive. Maybe if I ran higher amounts of test and added proviron I would get the sex drive boost people talk about.
NPP has proven worse for me than tren with respect to erections. I think it has to do with the lack of androgenic activity with nandrolone (and DHN conversion), in addition to prolactin issue. For some reason, my last run with NPP caused issues that Caber nor prami could fix. Only coming off of it got my erections and drive back. I'm hesitant to use nandrolone again personally.
Bill Roberts doesn't seem to believe in tren related prolactin issues. I've personally seen my prolactin levels get high on tren via blood work, even on low test (50mg prop EOD). However, I've never tried tren on very low test, like ~75mg/week. Maybe if more people tried that, or kept their estrogen levels quite low, the prolactin issues wouldn't be there. Bill roberts speculates it's mostly, if not all, estrogen related.