I believe the JA Dstar Repeater folks have a better idea with band identifier. Using call sign routing, ie., UR=/JP3XYZA the Band Identifier, 'A' represents the first repeater installed, and 'B' the second, or at least that is my understanding. You will most likely find a contact on their 'A' repeater, regardless of band.
Here in the rest of the world, 'A' represents 23cm, B - 70cm and C - 2m. There is no pattern of which repeater has the most activity unless you use jfindu or the like - http://www.jfindu.net/dstarlh.aspx?rptr=K5CTX It would be nice if the data readily available could be formatted in a more useful manner for setting up radios - something like an activity meter. 73, Steve NU5D