One of the EMSA SSCs used to simulcast. I think he said he did it just to hear himself, or just because he could, I don't remember why he said he did it.
I do know that the UHF is still monitored though. Other ambulances that run calls for EMSA or do mutual aid with them can talk to them on the UHF. Also, I've talked to them on my handheld within the last month on UHF.