I have it running in a testing setup for about 2 weeks now. 8 modules flat on the lawn (Maysun glass/glass 410Wp), the battery connected and tied to the grid with export power limited to 0 because my meter is ancient enough to spin in reverse (which is illegal to do here).

Which setpoints do you mean? I'm not familiar with all the terms, especially when they vary by manufacturer.

If you mean the power limit the Deye should put on the DC bar (i.e. put into the battery), that works reasonably well. If it's at 100% it will still charge a few Watts, but nothing severe.

The other meaning I could come up is the target power to draw from the grid when export is disabled (as in my case, for now), or when it is feeding energy from the battery into the house when I draw more than the PV array delivers. That's 20W by default, but can be user configured. This fluctuates somewhat strongly, but overall works out correct. I believe the reason isn't the software, but the poorly routed measurement cables: It uses measuring transfomers and the cables in my setup go tightly and parallel to the power line that connects the inverter to the grid. The electrician said that's not an issue, but I guess he usually measures 50A+, in that case the noise is negligble. Around the 0A point the noise has a much bigger impact. But that's easily fixed.
Eventually I'll use that option to prevent the battery from discharging when the car is charging over night (e.g. when I charge with 1200W, I plan to set the target to that value).

I'm not sure if I can configure other setpoints, e.g. the MPPT target voltage (which would be a nice trick to get shadow managment). I can define some other things like "from $x a.m. to $y p.m., keep the battery at $z%, grid charging is [not] allowed, powering on the external generator is [not] allowed". For testing the battery balancing (it has an additional Neey active balancer) I used that. And yeah, it can trigger an external 3phase generator to power up (not sure if the 1ph can do that).

As far as I could find, all options are exposed via RS485. I adjusted the sunsynk HA addon to work with the newer 3 phase inverters (sunsynk = deye rebrand; changes are already merged upstream). Only thing that I'm missing is the current limit set by the BMS, as well as other BMS data sent to the inverter (I did not search the published register map for that, yet).

What I can already say:

All in all the technical side is pretty nice; as said in a sibling comment, I could theoretically push out 12kW AC on a single phase if my local load is severly inbalanced. And the MPPTs are pretty flexible in how much power they can accept (as long as the sum is less than 15.6kW at all times).

What's horrible is the UI side. Some phrases are highly unclear, and requires knowledge of what the option actually does. E.g. "signal island mode" means "in case of grid failure, tie neutral to PE on the UPS output". In German installations that's always necessary, else RCDs will be much less effective. They would benefit greatly if they had a team of knowledgable translators.

Having to ask their support to do an update is also a joke; especially since they don't publish release notes. Also, the update power cycles the inverter, which causes the UPS output to lose power.

My 14.3kWh LFP battery has a 200A Seplos BMS. The inverter and the battery talk via CAN. In the BMS the power limit is set to x Amps. But the inverter shows a limit of (x/2) Amps. Now my battery should eventually operate a 140A continuous, but I'm not feeling to well about setting the limit to 280A and one sunny day having the two systems decide to get along and actually push 240A (the Deye's limit) over the connection+BMS sized for "only" 200A.
The solution is to get another BMS, but back when we formed the respective group orders, people didn't yet know of this incompatibility. Plus we were focused on Seplos because the Victron users felt it was imporant to get a BMS that would not disconnect the negative bus.

Still, for someone looking at a small plant with just a few panels and a small battery, it's a great value preposition. Especially when paired with a different battery/BMS. With the 8 modules behind the house (shadowed in the morning and the late evening) I had 105kWh PV and 120kWh grid power over the last two weeks. That's 1k€ for the modules, 1.3k€ for the smaller 1phase 3.6kW inverter, 1.2k€ for the 3kWh Pylontech US3000C, plus some cables and AC fuses for 200€, plus a DC fuse+SPD box (<100€ if DIY) = 3.8k€ for basic stuff. What's missing is panel mounting (800€?) and, depending on local laws, an electrician to sign off on everything.