O/B Y Kenobi or how to wire two stage heat pump and fossil backup with honeywell thermostat

Honeywell seems to be widely instituting balance point logic in trade thermostats. I'm trying to grok the theory of ops where you have the heat pump as 1 stage cooling and 1st stage of 2 stage heat.

So the TH2210WF and TH2320WF (i.e. Pro 200 series-not sure why the model number and series don't line up better. yeah you can see a 200 in the numbers although sure looks like 2000 to me and they designate their TH6320 as 6000 series but T6-go figure) will take an outdoor sensor to operate the balance point but the tech line is a little hazy on the wiring for the crossover between heating stages at the balance point.

they suggest I need a normally closed cutout relay to separate the heat pump and boiler but I think the logic actually is in the thermostat already. if you set the principle type of equipment on the 1st heating stage as heat pump then when the 1st stage heat is called my guess is that it makes Rc to Y and O/B (except there is different logic on some heat pumps so no one can tell me if that is the right guess as to what happens. or maybe it is NC to O/B and breaks the contact. And maybe there is a parameter to set that tells it whether you energize O/B for heating or cooling depending on your heat pump setup?)

then you have told the thermostat there is an outdoor sensor and set the balance point from that input (**** only allow 5 degree increments unless you want to spend double on the thermostat like for a TH6320WF, ie. T6 series) and when the outdoor temp goes below the setpoint and it locks out stage 1 by disconnecting Y from Rc and calls stage 2 by connecting R to W2.

Of course what I really want is one that takes an outdoor humidity sensor along with outdoor temp and varies the balance point accordingly so i'm not likely to want to replace the fleet with T6s until they address this or maybe can monitor amps and temp output or some indicia from the heat pump as a direct balance point predictor instead of relying on surrogates.

Meantime if anybody can tell me if i'm close to having the thermostat theory of ops right, I'd appreciate it. If there are other brands I should consider i'm not agin it. I do find the honeywell web and app interface pretty good with the wifi. worst design flaw is that it doesn't retain wifi settings through power outage so i'm going to cut the pigtail 120 feed to the 24V transformer on my SR503 and power that separately with a small uniterruptible power supply because these are airbnb units and I don't want to have to go in and reset the wifi at the thermostat every time there is a 3 second hiccup in the power.

But i'm open to other choices. Main reason to avoid the RTH models for me is they do not enable the parameter to reset the maximum temperature so that I can allow tenant/renter adjustment but within limits. I don't know if they enable balance point/lockout on stages (the residential ones default limit is 90 deg. farenheit. Not really sure why that seemed like a good idea . . . ). While i'm working through all this I just set a notification if the room temps goes above 74 so I can see what's going on. But bearing in mind the kind of operation I'm trying to accomplish, if there are other manufacturers thermostats you have had success with and I should look at lmk.