AGM batteries?

After cleaning the soot out of the x45 this weekend, and incorporating the 2 AGM batteries, I used the 2 AGM batteries for the first time last night. The temperature was really mild, in the 30s, but still a much improved sevice time. After 8 hours of running my voltage was at 11.8v. They did take longer to recharge.
The cables I need to put them in my sleeper will be put together this week, then I can get them inside out of the cold. Today I located a 3rd one to include with the agm bank, there's plenty of room in my passenger side toolbox for the time being to go ahead and include it too.

 

I mounted the three AGM batteries under the bunk last weekend. I'm pleased with their performance. Although I didn't use them continually for over 8 hours, and the temps didn't fall much below 20 degrees, the voltage never dropped below 12.3 volts. The heater ran continuously all night which is ok considering its heating the engine, bunk, & fuel tank. That's .5 volts for 8hrs with 3 AGMs compared to 1.2 volts for 6 flooded lead cells in 6 hours. That's a big improvement.
I believe mounting them inside and kept warm helped a lot. I ran 12' of 2/0 copper positive battery cable, 10' of copper 2/0 negative, & 4' 2 awg to the invertor. The microwave works faster because it draws a full 1200 watts rather than 900, just an added bonus.
I also checked to see if the engine water flow & the heater both were flowing the same. The heater sends the water to the engine then the bunk heater core and finally the tank heater and gets recirculated. Which I assume recovers a lot of excess heat from the engine for a few hours before having to keep it warm.
As of now I'm happy with the added performance, & convenience the AGM batteries provide. Considering how well they've done the Maxwell ESM could be a logical addition and actually eliminate the 4 flooded lead cell starter batteries. I'm thinking that way now.
Thanks for all the input and sharing of knowledge and experiences.