ddmetzger that functionality can be conferred to ANY arranger from Yamaha or any other brand, that allows for: (1) custom style creation, and either (2a) sync stop; or (2b) the combination of arranger "hold" and "retrigger."
I agree that it's a very useful configuration for practicing, or covering religious music that doesn't have percussion, and doesn't follow a uniform meter. But it shouldn't be pivotal to your buying decision for the reasons I stated above. I have personally imparted this feature to Korg, Roland, and GEM keyboards that did not have it as a native function. It's just a special and creative use of the features that are already there!