I don't believe that an XLR that was driven regularly would require a trickle charger or other device if an Odyssey AGM was installed. I use the optimizer to keep mine "topped off".
If I recall correctly, an XLR has 23 serial data modules, which certainly would contribute to battery drain.
Here is a picture of what the displays on the Optimizer show with a fully charged battery :
13.2 volts
Which is a 100% charge.
But let it sit for a few days and here is what you would see :
A 75% charge and 12.5 volts.
And let it sit for 7 days and this is what you see :
60% charge at 12.3 volts.
Now, granted that this "loss of charge" is what is often referred to as "surface charge", but it illustrates that there is a constant drain on the battery in an XLR.
I have little doubt that my XLR could sit for several weeks without ever being connected to the charger and still crank just fine. But I like to connect the Optimizer weekly to keep it at a high level of charge. The Optimizer slowly brings this charge back up, rather than a rapid recharge such as would be experienced by starting and driving the car.
It's just a personal quirk that I don't leave it connected all the time, but rather connect it usually on a Saturday or Sunday afternoon if she hasn't been driven.
.... sans Opitmizer 
