My surgery was just 2 weeks after yours and my wife and I are also experiencing ED frustrations. In my case, my surgeon indicated that he spared more than 50% of both nerve bundles. He also emphatically stated that nerve bundles do not grow back. They do heal over time, but do not actually increase in length.
Since my catheter was removed, I've experienced erections which are about 50% of pre-surgery rigidity. With ED meds (I've tried full strength of Cialis, Levitra, and Viagara), I get an extra 10-20%. This is via manual stimulation - the days of just thinking about or seeing my wife naked and having an instant erection are apparently gone.
On only 2 occasions (of twice weekly attempts) since surgery have I had an erection sufficient for penetration. Both of those times, I rather quickly lost the erection and was unable to "satisfy" my wife sufficiently. I do have a pump and have found the rings to be too painful to use for intercourse. At my 6 month visit I intend on asking my doc for either a Bimix injection or gel.
Again, at this point I'm quite frustrated and (like 56pontiac) worry that I've leveled off and will never achieve a penetrable erection. I am heartened by his post though.
Not sure if this helps or not, just thought I'd add my experiences thus far to this thread
Diagnosed at age 40 (March 2009) as a result of routine physical
Family history - Father diagnosed and treated at 64, one of his brothers at 70, maternal uncle at 60
PSA 19.14 (first PSA), pre-op PSA 3.93 (second PSA)
1st DRE - abnormal - 1cm nodule - 2 subsequent DREs by 2 different surgeons showed some firmness on right side, no nodule
14 biopsy cores - 1/4 positive on left, < 5% malignant, 3/7 positive on right, 10% malignant, 3 cores of nodule showed no malignancy
Gleason 3 + 3 = 6
Cat Scan - negative, believed to be prostate confined
Bone Scan - negative, no distant metastasis
Davinci RP performed 6/1 by Dr. Jean Joseph at Strong Hospital in Rochester
great wife and 3 young children (ages 4, 6, 8)