I will add my 2 cents for what its worth, but those nerves no matter how much they are being preserved , they are pulled and pushed on during surgery, and like any other nerve in your body take a long long time to heal, especially with a delicate process like erection.
I think that you husband actually doing REAL well and way ahead of the curve at the time period you at ....if you already can have him have a soft erection , partially and an orgasm , it is truly great , most men after RP do not have any progress for at least 6 months.
I had an
open RP back in June 2007 , just over a year now , and only at the 9 months mark start feeling some significant changes , and progressing slowly since then , but at my one year visit my Uro assured me that i am doing a great progress with 70-80% erection without any assistance and almost at 90% usable erections with generic Viagra.
I also start using the pump at the 6 month mark for rehab , and ********** at least 2 to 3 times a week as well.
positive attitude , patience , and rehab is essential for a faster recovery.
i hope my experience and thoughts can help you and hubby ..
Keep us posted ...