https://www.generac.com/residential-products/standby-generators/gaseous/standby-generator-10kw-wifi-enabled-7171/

Like I said, the hiccup was small, the lights flickered hard but not severe enough to make devices and appliances restart. I only did one cycle, I'll do a few cycles tomorrow to see how it's working. 

The good is, I can set up my gen settings to what the gen can putout and not have to worry any longer. It started up, ran long enough to be stable then made the switch over seamlessly. It ran the loads and charged the battery as you'd expect, I'm pretty happy with it. 10kw isn't nearly enough to run my house, but it is enough for the pool, appliances and lights while charging the batteries at about 4-5kw.  

Tomorrow I want to see what happens when I exceed the max gen input setting and have it cycle charging a few times. 

Will report what I find tomorrow.

https://canadianoffgrid.com/products/briggs-stratton-powerprotect%E2%84%A2-dx-20kw-standby-generator-040657?utm_source=google&utm_medium=organic&utm_campaign=Multifeeds&utm_content=Briggs+%26+Stratton+PowerProtect%E2%84%A2+DX+20kW+Standby+Generator+040657&gad_source=1&gad_campaignid=21458987489&gbraid=0AAAAAoXkUuzJuU0EwIhYZFY_0Q9ofshuq&gclid=Cj0KCQjw4PPNBhD8ARIsAMo-icyTQOZM2prcOGFFA2KYZXSnU5jQ_hOsy8RXoHNCfAkX1Km7Wv2FAaAaApXZEALw_wcB

With the last firmware update ceaa-0709 Generator Switching is fixed. Switching from batteries to gen power is seamless and switching from gen to batteries has a hiccup but it’s small. Good job EG4!  

I'll have to wait for better weather before I can do a test, but from what I'm gathering here, genboost works as intended, but when the generator starts and it switches from battery to generator, you're getting a 1-2s blackout?  This sounds similar to an issue I think they fixed in the most recent firmware, where if you were using battery eco mode without solar and lost grid, it would cause a 1-2s blackout when switching to battery. 

The Chargeverter is supposed to do a warm up and cool down cycle, so it starts your generator and waits before it draws any current, then before it shuts off the generator it let's it idle for a bit before shutting off.  Does the 12000XP not work like this?

I bought the Chargeverter already, but my wiring would be so much cleaner if I just used the 12000XP's generator input.  I also have all 50A gear for the generator and using the 30A chargeverter with this is going to force me to add a breaker box as well.

I disabled my exercise program on the generator and this helped for the first charge - there was no issue, but last night it was -30 degrees and my inverter called for generator power.  It then sent my inverter back to 50Hz.  I know the cold will reduce starting idle, but the inverter should accommodate with a delayed charging feature or warm up feature (as some of you above have suggested). I'm not sure what the time required for warmup should be, but I'm sure 60 seconds would do it for almost any generator.  This is definitely a software issue.  Alternatively, the inverter should have a setting that can be set to only accept power within the appropriate parameters (59-61 Hz for example).  This seems to be a pretty simple fix.

I'm 100% off grid and if the gen fires up at night and I don't notice it, this lower frequency will fry my furnace fan motor.  Then I'm in a heap of trouble!

If anyone has a workaround, please let me know.  EG4 has not been helpful, even denying it is a problem and blaming my generator.