I like the combat shotgun, though it is overpowered at close range, its weakness at long range makes it somewhat fair. If you're going to talk about people on bikes being too powerful, what you really need to talk about are the people who ride on things with snipers and rifles. Anyone can usually take some combat damage, but losing tires from ridiculous distances gets impossible to deal with, given enough VIP terrorists.
...the terrorists NEED a bit of extra oomph if they're gonna stand a chance against 5 securities shooting at the bike from one car + all those cops trying to hunt them down + the sniper jetpacking nading civilians.
I think if anything needs to be changed, the President needs to be able to drive things that allow him to avoid the combat shotgun DBers. In LS, for example, there are basically no cars in the vicinity of the President spawn that are fast enough to stay away from the combat shotguns. The good and fast cars aren't spread out; instead they're all in the terrorist spawn and the civilian spawn. Practically all the maps have this problem, except for FC, SF and LV. Flying presidents can also avoid the combat DBers without making things unfair... *cough*