I expect it's partly due to the market ecosystem when DMR was created. The standard is codec-agnostic, but in practice DMRA (and thus all the manufacturers) set

I expect it's partly due to the market ecosystem when DMR was created. The standard is codec-agnostic, but in practice DMRA (and thus all the manufacturers) settled on AMBE. If APCO P25 predated DMR, that'd at least partly explain the codec choice. I'd absolutely love to see a Codec2 based DMR radio, even if it were a firmware mod to an existing radio. As for the degradation - same. The only data I've seen is from radio manufacturers and the DMRA. Practically it's going to depend on the specific radio, the antenna and so on. You could measure sensitivity as dBm vs error rate for digital or dBm vs SINAD for analog and plot the two together. Once you cross the line of what the ECC/FEC can handle, things tend to break down very quickly. Most DMR radios will cut out entirely if they see a lot of Post-FEC uncorrectable bit errors.