I have both and haven’t used the Power-Jelq in a long time. Manual methods are just as effective and your arms still get tired. Some guys find it difficult to use because of the shape of the penis. Most penises are oval because of the twin cylinders (corpora cavernosa) side by side. The PJ is fairly easy to use on the top-bottom, but difficult to use on the sides. A lot of users are afraid of being too vigorous on the top-bottom for fear of nerve or vein damage. You also don’t get the blood trapping you do when you use a two-handed jelq method of clamping the base while stroking with the "OK" sign grip of the other hand. I actually took advantage of their "second one half-price" (or whatever it was) at the time of my purchase. The second one is still in its unopened mailing pouch. My advice: buy a pump.
You can work on girth with a pump and cylinder if you get the right size cylinder. Most guys starting out try to work length first by getting a cylinder only slightly larger than their current measurement (penis diameter). When you "Pack the tube" with your present girth, the vacuum is directed more at length since the cylinder walls prevent much lateral expansion. Although some have made gains using the pump alone, I look at it as an adjunct to manual methods. Gains by pumping alone take some time to develop.
The fat cocks you see on pumper sites are due to the long, long pump time and high vacuums used by those guys. This pulls lymph fluid into the tissues and results in the bloated look they like. For PE you should pump with low pressure (4 to 6 inches of mercury - Hg) for short periods, three 10 minute sessions with rest between. This puts stress where it’s needed and avoids the problems of fluid migration. You should also enter the tube erect as this also helps reduce fluid leakage into the tissues.
There are dozens of sites that sell pumps and cylinders. You can also check sex shops. LA Pump Distributing has good products and is often recommended. Be sure to buy a pump with a vacuum gauge (such as the MityVac ). Don’t buy the cheap ones with the bulb or one without a way to measure the vacuum. You can find MityVac pumps at automotive supply stores.