BTW the stainless ones from MVS are mix and match some having the black cup others having the white one..they must be phasing out the white rubber..they all have the black o-ring on top of the cup..that o-ring seems to work better because it's flat and has a channel to hold liquid. I know what you mean about the black rubber cup OP when one gets too close to the coil it tastes like rubber..but if you pull it away from the coil it is fine. I've only had to adjust one so far because of the rubber taste though.
The white cup does the same thing if it gets too near the coil but just doesn't give off as bad a taste as the black one. One way of fixing it is pulling the cup out a little but also you sometimes can carefully pull the wires that go through the ceramic with the CE2 apart and it moves the coil down a little..not too tight though because it can break the wire and the wicks can be against the ceramic too tight..once you pull the wire a little you can bend it over and it will hold the coil from moving up. BTW you could also take the white rubber cups out of old CE2's wash them and use them in new ones..I keep all my old CE2's for rebuilding and various reasons...
We keep all our old clearo parts too for exactly that reason. I know you can get a burnt taste from the white plugs too if they get too close to the coil. It seems to me the black plugs are just nasty out of the box whether they actually come into contact with the coil or not. They're also a softer durometer, so I've shredded more than one trying to get it out of the tube. What a mess.