It's interesting reading all this, as I hadn't seen the thread until this morning.
I was asked last summer to help a friend upgrade his 40' sailboat's house electrical system. The prime motivation was to upgrade to 12V 560Ah (4S2P) batteries, but in the process he decided to upgrade to mostly Victron stuff: A Smart Shunt battery monitor, a Multiplus Compact Inverter/Charger, 2 MPPTs, a Cerbo GX, and a GX Touchscreen. He's was upgrading to a Wakespeed WS500 alternator regulator.
I knew from reading about it that a risk in charging LFP from an alternator can be that the BMS cuts of charging so that there is a sudden drop to zero on the current, which can cause the alternator to burn up in short order. The system we're doing will have two DC-to-DC chargers from the LFP to other banks on the boat, and I've read that can be enough to prevent a problem. In addition, I believe the Wakespeed also does something to deal with this risk, like maybe cut the stator field current. I don't really know anything about the Wakespeed (or alternators) so I'm not sure about that.
Mostly because I already knew them, I went with two 4S 150A JBD BMS's. I was building the battery bank when I decided to start asking about what I needed to know to have the Wakespeed show the amps out of the alternator on the Cerbo, and how best to display battery status.
Almost immediately I started getting some real REC enthusiasts (maybe zealots?) that I was doing it all wrong, and that I needed to go 2P4S and use a single REC BMS, because it could integrate with the Wakespeed to "manage" the current coming from the alternator. This kind of puzzled me because I thought (as
@upnorthandpersonal said) the LFP's kind of manage it themselves. They will take as much as then need, and when they are full they don't take much. I did know that the passive balancing can perhaps work better if the current is decreased near the end of the charging, so that the final absorption phase takes a little longer.
I mostly gave up asking questions, because it seemed like if I didn't agree to go REC everyone that it was going to be terrible.
He's now in the process of completing the installation. The Wakespeed connectivity to the Cerbo GX is one of the last things (he needed a longer cable). I'm still not certain that the Wakespeed will provide the alternator current to the touchscreen display, but I guess we'll see.