It's more of a behind the scenes thing Alaris, and something which Ultimaker will need to do sooner or later with the way they are growing. Having to rely on third party electronics and their supply chain can be quite harmful to sales - if they cant get in an arduino board, or a shield, or the stepper motor driver, they cant sell machines. If I could hazard a guess at what is causing the delay in shipping new ultimakers, I'd be pretty certain that it's 3rd party parts and not any other sort of backlog, be it stepper motors or electronics. It's not practical to develop and manufacture your own mechanical parts, but it certainly is to make your own electronics. You can source hardware from many companies, but electronics are usually fairly specific.
Having more clock cycles per second, and better code can improve print quality, as commands can be executed faster and there is less change of missing steps or microsecond pauses because the software cant run the commands fast enough. More accurate timers for executing steps or doing finer microstepping also gives you a smoother print quality. Having more time to handle a user interface or even being able to have a networked interface to the machine also opens up more userfriendly options for printing with the machine.