Interesting question. I am curious as to Riveraddicts read on this as this seductive up and down would seem to fit his Intruder quite well and I can surely see where action would play an important role.
Part of me says that the variations in color would make little or no difference in most cases but your theory makes as much sense as any. Undoubtedly some colors on some days under some conditions just tend to piss off some fish some of the time. Why that is, I have no idea. If it works for Fred though, I say don't fix it.