I tried the Vacurect pump with the discs also, and found them to be painful and not very useful. The disc's are designed to keep the scrotum and assorted other body parts out of the pump. Like you said, it does, but at the price of being difficult to put on and even more so to remove. One trick they mentioned that I missed for a while was to gently squeeze the erection to push the blood back out, then to remove the ring. I found that with enough grip, I could semi-stretch the disc for removal after squeezing the blood out somewhat.
I bought a set of soft silicone rings, and use them with the Vacurect pump. With a little practice, I can put a silicone ring on the end of the pump and place it on the penis when needed, with no pain, pinching, or problem. Removal can be immediate, by grasping the wings and pulling out and off. Here's the link.
Use Tiny Url: http://tinyurl.com/4we3pz
or the full one below. It wraps, so you will probably have to copy and paste, maybe
I got the kit with the plastic cone, for later, if and when I don't need the pump anymore, but might still need the rings. lol These rings work really well, and don't remain stretched after use, but shrinks back to their normal size for reuse. they are a big step beyong the Vacurect disc's. I'd recommend them to anyone with the hand strength and dexterity to apply them to the end of the Vacurect pump.