Longer than 16-character alpha tags. I don't see why it's not possible, they can scroll the words Scan and Search, why not scroll a 17+ character tag? It may not happen often, but every now and then I want to tag something longer than 16 chars.
Better support for duplex systems. And no I don't mean a true duplex system where both sides transmit at the same time, but the typical taxi-style systems where they take turns, but each side is on a different frequency.
It would be nice to be able to identify a pair of frequencies as a 'duplex set' - then after a transmission on either of them and during the delay period before the scanner resumes scanning, it should look for a transmission on either frequency. It always sucks when one side stops transmitting, your scanner resumes scanning and you've got to wait 5 seconds or so for it to come back around again, and by then you've missed the reply...