It appears the original poster had his questions fairly well covered. I feel the need to add a few notes:
I can speak of the Dr.Kaplan and Vacu-Tech products. Indeed, you get what you pay for...quality.
Interestingly, I was able to "interchange" the pumping cylinders between these brands.
I was concerned in reading the posts here about "guessing" at the corrrect pressure. This is somewhat risky business, guys! --believe me.
I bought the Kaplan (electric) system several years ago when I began PE. For whatever reason, one of my acrylic cylineders developed a problem with the "snap" air-line connection. Foolishly, I continued using it. The Kaplan vacu-pump system used TWO kinds of cylinders--one for just the penis and another for the penis and scrotum. I was using the penis/scrotum cylinder (which had the airline connection problem) and THOUGHT my "pressure" was well within safe limits. Afterall, it felt good! And, my pressure gauge was within what I had been using. And, I had worked up to three (fifteen minute) intervals (daily) after a number of months using it. Upon removing the cylinder, I noticed strange "sensations" in my scrotum..(right side). Somehow, unlike many previous sessions, it just didn't "feel right" .
My scrotum didn't necessarily "hurt" but, it felt achey and tingly...not what I had ever experienced before after pumping. I started to be concerned.
Within hours, my scrotum was really quite swollen and the right testicle could not even be felt! Later that night, my scrotum was beginning to show discoloration. Next day, my scrotum was black and blue --COMPLETELY on the back side of it. Meanwhile, my right testicle was still "unfelt" and I had considerable puffiness in that side of the scrotum. I was scared silly and not sure just WHAT to do. When I "jacked-off", my ejaculation felt "blocked" and incomplete. It was like I could NOT get the sense of relief and release I should have gotten. The semen amount was less, too. Something was definitely very wrong and I knew it. My imagination was running wild.
I had hurt myself! HOW would I seek help from an MD and admit what I had done! I figured I would be sterile for life!
Not being in too much discomfort (except mentally!) I allowed the black and blue symptoms to disappear along with some of the swelling (like about two weeks!) and THEN went to a urologist to get checked out. (I know...what stupidity, uh?) I reluctantly told the MD what I had done. He didn't laugh, but he didn't advocate my PE procedure either! He ordered an utra-sound test to determine the condition of my right testicle (which was still there, but VERY much hidden by fluid). Most fortunately, the gland proved not to be damaged but was badly traumatized. It did take about three months for all the swelling to subside and things to return to normal. The scrotum discoloration had of course resulted from internal hemorrhaging. I still have (scar tissue) a pea-size lump in the spermatic "bundle" cords on the right side. The MD says not to worry...the lump is not attached to the testicle itself. It 's not a matter to suspect a malignancy resulting from that injury. The MD noted that over a long period, this lump may resolve on its own. (Long car trips still seems to make this lump get sore in feeling) My ejaculations did FINALLY returned to more normal. All this was a very frightening, but valuable lesson to me (and now, perhaps to others.)
My point to this story is to be careful pumping. Use good judgment and don't leave the pressure matter to second-guessing. Take it slow...very slow.
Pumping usually will improve girth over a very long period of time. I'm still convinced however, that using at least several "other" PE methods seem to bring the best results overall.