The Erotic Highway
Dear ED_Victim,
I can understand your dilemma. I've actually been fortunate enough to witness the vacuum pump at close range, so I will give you a brief personal impression - which probably is as good as anything else you'll read, since there is absolutely no one-size-fits-all in terms of experience.
Pro's: Erection was effected and maintained until ejaculation, making all and sundry pretty happy.
Con's: It's not a small, handy little tool. If you have to go somewhere, the vacuum pump goes with you in a "discreet" bag. You definitely have to haul it out, put your penis in and start pumping. It's not a lengthy process, but it's not particularly "graceful," if you will. It's a mechanical process, complete with tube and all, no motor involved. A few suction pumps and the penis is up; it's rather efficient, I must say, and certainly more "natural" than some other remedies out there.
To me, it wasn't a turn-off; in fact, I was relentlessly fascinated and amazed that the penis became erect, just with some pumping effort on the part of the guy. It wasn't a straight ride from petting to insertion, though; action was interrupted in order to pump-it-up. Did it cause any discomfort or negative emotions on my part? Zilch. I'll never forget it, it looked that "neat and interesting." And clearly, we did enjoy ourselves, what with all the fun things that one can do with an erect penis!
So with the blessing of your physician, I definitely would recommend a try. Why not? As to providers, just pick an experienced professional and you'll be fine. 
One for the memoirs,
The Love Goddess
After seeing a picture with that gauge in it, and having worked with hydrolics and pneumatics, I felt pretty intimated by having anything on my penis that needed a gauge. I know it's for safety's sake, but I've also seen the consequences of gauges that didn't work properly. Please don't think I was saying this issues was not important. There's no telling if and when I'll be trying the same thing.I just need to remember how to calibrate gauges.
it appeared like a big plastic tube-within-a-tube. It had no additional attachments. I can't even remember the cock ring that apparently goes with the piece, but then again we WERE having fun, so...
Proof that the erotic haze still rules 
The Love Goddess
She saw him for several years on a regular basis and he was always able to get erect and achieve orgasm using it.
Like LG said, it's not conducive to a romantic moment, due to the break in the action and the functioning of the device itself. But I think both you and the provider know why you're there, and it's not to seduce her or impress her with what a stud you are.
She's a professional at your service, so just think of it as another toy to be utilized in the process of achieving your pleasure and be glad you're still having some fun. Hey, if it's good enough for Austin Powers...