Just a follow-up.
Earlier this year, I tested both my CTEK 3300 units at work. They were charging a new battery that was confirmed good. A Graphtec data logger was used.
My CTEKs did not enter any "maintenance mode". They simply charged the battery to 14.3V and then switched off, turning back on at 12.65V.
But as I mentioned above, I prefer this method of battery maintenance...its just not doing what they advertize.