Question 18kpv and Franklin Batteries vs EG4 Batteries

Looking for some advice here.

I have 12KW solar connected to an 18kpv and a couple of 100Ah batteries that provides backup to a critical loads panel. In an outage/backup scenario it does not provide enough power output or capacity for whole home backup.

To solve this I thought I would get a gridboss and a flexboss along with 2 x 314Ah (16kW) batteries. Connect gridboss to main panel for whole home backup instead of just the critical loads panel, connect flexboss and 18kpv to gridboss, connect one battery to flexboss and one to 18kpv for load balance.  This should double output power and significantly increase capacity. Maybe add more battery capacity in the future.

I got a quote from an EG4 installer for the gridboss, flexboss, 2 batteries, and install for approx $36k

I also got a quote from a different company to install an aGate and 2 x 15kW Franklin batteries (ac coupled to the 18kpv) for approx $32k. This also provides 20kW of output power as well as the same capacity, all configured for whole home backup.

I'd heard Franklin was expensive so I was a bit surprised the Franklin solution turned out to be actually cheaper than EG4 solution, and seemed a lot less work removed link It seems EG4 equipment is pretty reasonable priced but the installation must be way more complex because the overall cost is crazy?

I'm kind of stuck deciding which way to go, even considered just buying a generac and connect to the 18kpv because that's actually the cheapest and simplest (but not optimal) option!

Has anyone got experience of Franklin batteries used with EG4 inverters?  I am leaning this way at the moment.

Anyway, any advice or feedback is appreciated.