The backup repeaters get tested a few times a year, that's how I got the tones for them. Peoria PD keeps them in the event that the RWC has a widespread failure. Those frequencies used to be used for the City services trunked system, prior to the RWC.
I hear 8AIRS-AZ come up once in a great while, although usually with a 100.0 Hz tone, and sometimes with interference that sounds like an open squelch knob. Especially in the area around the ASU West campus.
460.3500 at the stadium is active fairly regularly, with maintenance comms. They're more active when there's something going on at the stadium, of course. I think you should be able to hear them.
National Itinerant 3 is the only one of the three National Itinerants that I've heard, and I'm pretty sure it was encrypted every time, although it's not supposed to be encrypted at all.
And the correct Alphas for the 8Tacs should be 8TAC-91, 8TAC-92, 8TAC-93, 8TAC-94, and 8TAC-95.
John
Peoria