The real question, getting back to the OP's situation, is how many times can the one AGM take an occasional 60a draw before developing an "internal fault" like full mosey's did. Then know how many times you will do that over the years.
In my case toss in occasional 120a draws for the microwave, and 80-70a draws for kettle and toaster, which look impossible with the one AGM. Two AGMs would be like one doing 60a draws for that.
Looks like one AGM in this role would do the OP's toaster and coffee maker 60a jobs occasionally, so he is likely ok, but I am across the line where I would need two AGMs. (so toss in the T-1275s :) )
OTOH it does seem possible that two AGMs could perform the same role in the 5er in summer with solar as four 6s do now. One of these AGMs is only $50 more than a T-105 around here. Hmmmm.
EDIT I am liking this whole single AGM idea better and better for the TC in the same role as the OP's (thanks OP! :) )
For unplanned or short off grid times it will run the low amp draw stuff like the 3.2 cu ft electric fridge (high priority item!!!) in the TC plus TV/DVD use, etc, and maybe even the toaster.
For planned off-grid for longer times away, the T-1275s can run the big stuff using their own inverter. The T-1275s can't be banked with the AGM like they can now with two 6s in there, so that means a split bank. No sweat, done that before in the 5er. Needs two inverters and a solar set for each bank (got that already from doing it in the 5er a couple years ago.) Just have to invent a new hodgepodge of 120v wiring plug- in scenarios for the TC without using automatic transfer switches, but that is easy stuff. Hooray! :)