I have never had any problems with the double sided tape that comes on the champion easy hit sight, but I use electronics cleaner to degrease the rib first. I never cared for the way those thick double sided tapes made the sight sit up off the rib though. I found that permatex black rtv silicone holds them very well and I could get the sight all the way down on the barrel. That way, when I look down the rib they actually look like a glowing bead instead of a big, add on contraption mounted on the end of my gun.
On my bps and the Maxus I had I degreased the rib, smeared a very thin layer of rtv on the bottom of the sight, put the sight on the rib, wrapped it with thin rubber bands (I cut the rubber bands and tie the ends together so it makes a long, thin rubber cord), get the sight centerd up perfectly, then leave it alone for about an hour. Don't touch any of the silicone that squeezes out until its almost dry. When the silicone is dry to the touch, remove the rubber band material and use your fingernail to remove the excess that squeezed out.
If you ever decide to remove it you can use fishing line to floss between the sight and rib but the rtv will be a bear to remove from the textured surface of the rib.