Maybe someone already posted this somewhere in the forum, but if so, I didn't see it and wish I had before dragging my luggage to their old location. So I thought I'd post it again. The immigration office is now in one of the booths right in the check-in area at terminal 3, near the end of the terminal where the escalator up to security is located, and next to the hallway going to the bathrooms (directly across from the Sun Country Airlines check-in area). It was very convenient and quick to get my salida for my FM3 at the new booth!
Yes, the new location is much more convenient. And it's harder for agents to solicit bribes in that location too, so that's good too.