Charter services are another point that will help one ride and hinder another. I doubt that many of them will be able to have a presence at both rides. Charters not only provide services that RAGBRAI doesn't have to and that many, many cyclists want, but they also require registration before they'll let you sign on. Everyone using charters is a paid RAGBRAI registrant, unlike up to half (by some accounts) of the general ridership who ride bandit for a day or more.
Bubba's has already announced that they will be at Iowa's Ride in 2020, NOT at RAGBRAI.