Following the chase rules:
1. You leave your downed comrades behind. Again, very unlikely that friends at a table are going to opt to do this.
2. You're essentially wasting a turn NOT fighting. Chases are still done in initiative order. Instead, you're running away. Your enemies will get a free round of attacks, and then start pursuit of whoever else is left.
3. This seems like a tremendous waste of table time, when there are other games with simpler retreat systems in place. Not only are you going to be spending time, turn by turn, trying to escape- your downed friends are going to be sitting around waiting for it all to end as the fleeing players with fleeing characters basically have to experience defeat in an excruciatingly drawn-out, desperate fashion. This is the worst kind of slog gameplay.
I like simulationist rules in many places, but in the awful parts like realizing that you're going to fail and have to just try to survive, I'd like those parts to be brief but poignant. Obviously this is my opinion- maybe there are players that enjoy what I consider an awful morale-shattering slog.