Based upon my personal experience and from conferring with other patients and my urologist, some of the benefits that I believe come from using vacuum pumps are:
1. Therapy for penile tissues (this assumes ED is present)
2. Increasing blood flow in the pelvic area, which may help some with incontinence (Viagra may help some here, as well, for the same reason)
I know of a man who suffered from post-surgery ED, did not use a pump and had a penile implant. Due to some issues that I will not go into here, he had the implant redone a few months later. The second time around he used a pump for 2 months. His result the second time yielded 1.5 more inches in length than he got the first time an implant was done.
Just some general info, for those considering a pump.