Adding More Solar Panels

I'm not familiar with the Xantrex 40. Why replace it? What is its weakness for your usage?

No real weakness, my only grip is once the batteries reach the set bulk charge voltage, the controller holds for one hour and drops to float

voltage has to go significantly below float or a sunset cycle, for the bulk mode to kick back on

batteries can be absorbing 16amps at 14.6 and it will drop to float 13.7
and 11 amps charge
fridge kicks on and draws 9amps of the 11, solar stays at 11amps 13,7v
batteries get 2amps while fridge is running, then back to 11 when fridge stops cycling, if i'm on the PC, it actually goes into deficit mode, inverter using more than what the charge rate is, and the Xantrex does not kick it back up, until it decides the battery voltage has dropped enough
thats my only gripe
newer controllers work different were "Vtabs" is charge and float and the controller will attempt to maintain the set volts
this is advantages where you have daytime power use, but must be carefully selected and can not be as high as I like , because of when you are away from the RV and not using power and don't want to subject the batteries to many hours at 14.6v

what i want is to maintain bulk voltage until amps charge is low ( some preset ) then drop to float, but come out of float as soon as there is load and float voltage cannot be maintained
but nobody is making what i want