The answer to this question used to be no but that’s changing. Now the answer is, it depends.
If you are talking through one of our repeaters to a person on a different repeater on our system then yes, absolutely. Because we use the MMDVM controllers (and some extra special magic smoke) on our repeaters this isn’t a problem. You’ll regularly hear a mix of radios modes being used across the system.
If you want to talk to someone that is on the same repeater you are using then the modes need to be the same. Also, if you want talk radio to radio in a digital mode you’ll need to use the same mode (but don’t forget you can still use FM to talk radio to radio if you’ve programmed FM channels into your radio).