Thanks to everyone that responded!
I had already separated the fire and police department's into separate systems a few weeks ago when I ran out of space. I have fire/police "scanning." I have about 80 talkgroups in the fire bank (Fire Dept./Hospitals/Interoperability Talkgroups), with a little over 250 Unit ID's. So it is allowing me, for now, to add more than 250 unit ID's in my "Radio ID's" group. We'll see how it goes.
I have all the fire engine's, most ambulances (front and rear radios), fire/EMS chief's mobiles and portables, hospital base radios, and Lifeflight's subscriber ID's. As for police, I have a few of the special units, and a few buddies radios listed. Regular patrol would be astronomical. I put all the radio ID's in a separate group "Radio ID's", and when they talk on a regular talkgroup they are displayed on that talkgroup respectively. It's a pretty neat feature.
I was wondering if a firmware upgrade could "unlock" more unit ID's per system since the scanner has so much memory for other systems. For example, I have a Motorola XTS5000 that had 850 or so channels, and when I think version 11 or 12 firmware came out, it upped it to 1000 channels when I had it flashed. Just wondering.
You can actually have a system with no talkgroups programmed in. The only reason for this would be for private calls (radio to radio). I monitor these pretty much daily. They don’t use a talkgroup when in this mode. You will just get a Unit ID come up, with no talkgroup.
I agree with "cellphone's" statement that 500 is limited. There are folks in public safety that use scanners as well, and could really "use" this, since scan lists are limited in two-way radios.
Again, thanks folks!