The XTL 5000's, XTL 2500's, XTS 5000's, XTS 2500's, and XTS 1500's can handle P25 Phase 1 digital systems. Not sure what other older gen radios can.
If your dept. is using TDMA talk groups in the future you might as well get a scanner unless you want to spend thousands of dollars on a radio.
Using a radio runs a risk of it being bricked. On digital systems, the radios will attempt to affiliate with the system, meaning the dispatchers can see it, and the dispatchers can and will brick unauthorized radios affiliated with their system as it can cause problems. If you don't have approval from whoever manages your radio system, and you don't have someone that knows what they're doing when they program your radio, I'd advise to stay away from using an actual radio, a scanner is much more user friendly and you can get a wide variety of traffic vs just one freq band.
Scanners do come with a drop in receive quality though. They can't match real radios.
Don't forget to consider other brands besides Motorola. ICOM and Harris make P25 capable radios that sell for much cheaper than Motorola's its just harder to find them on the used market because Motorola is such a big player.
Disclaimer: I'm not a radio expert. I recommend checking out radioreference.com for more info