Not saying you're wrong, but are you sure that Dinosaur really under-goes more work than any attraction at Animal Kingdom? While I'm sure it takes a decent amount of work to maintain, I'm willing to bet the constant maintenance of the 44 different Kilimanjaro Safaris vehicles rivals the work done on Dinosaur.
Also, that Primeval Whirl rumor must be a pretty wide-spread one if you feel it's not true because I've heard the exact same things that were suggested by MythBuster.
I am sure the Safari trucks undergo a ton of work, I am sure they hit more things then Disney would admit to. I have never had the pleasure of seeing their facilities for repair. However I do know that Dinosaur always has at least one or two vehicles in their shop being worked on and always at least one being taken apart down to its frame, reworked, and then rebuilt. It needs the most work because believe it or not its actually one of Disney's most dangerous ride vehicles due to the shear amount of force each car uses.
The Primeval Whirl rumor is just that, while the ride is in dire need of a refurb, the attraction is not having problems like some claim. Parts are not falling off and the attraction is not having problems as to cause it to have a major problem. The only problems I have ever seen there is a car wont lock or unlock for spinning and the lap restrains locking system fails to disengage - all easliy fixed by operations within seconds. The system that certifies the attraction has more fail safes then any coaster I have seen in its class, the attraction is checked multiple times each day by operations, it is maintained each night by engineering, and is always being monitored by operations, engineering, and the ride system.