Yep. To me I would not use anything but rubies. It's clear that ceramic works similar to boro, so you'll need more heat. It will also take longer to go through a bowl at those higher temperature. You can find lots of videos online that illustrate this, but you'll definitely see that you can drop it down about 70-100F by using rubies. The phase3 thread has some examples too.
Zirconia and SIC have their uses, but for heat retention, I haven't seen anything beating rubies.
Different size rubies will affect your airflow. This comes down to personal preference, I think.