Downsides of the open-source modem firmware?

[alaraajavamma]

Are there any downsides of using it instead of the original firmware?

I'm no expert, but I remember reading that using the free firmware would probably be illegal in most countries. Something about being able to change your hardware identification.

I don't claim to be 100% right, but I'm pretty sure of the below - please correct me if someone knows better

Biktorgjs modem it not replacing the actual "modem black box" thing which is that "secret" and legally controlled technology. ADSP is still the same as in stock firmware and ADSP is the part which does the actual work of the modem, i.e. makes a connection to cell towers etc.

Biktorgjs modem replaces the userspace so it gives more control between the modem and the phone's own user interface.
I have several pinephos in daily use. I'm not a developer, but I'm an active tester and I can't figure out a single thing what was better in stock firmware.

But because worldwide carriers work differently, your experiences may be different from mine (even though I have tried with three different carriers)