The charge settings for AGM are very close to Flooded wet and Maintenance free, ENough so that as someone pointed out in cars they are basically interchangable..
I have one and only one complaint about AGM's and in the Original Poster's case it does NOT apply.. COST.
Of all the battery types out there AGM is the most or 2nd most (Actually both) Lead Acid type battery.. (OPTIMA is the most expensive but it is a special case of AGM so that is how AGM can be both) but since the post started out with "I was given" the cost was ZERO and it's kind of hard to beat that price :).
For RV use there is next to no advantage to AGM and the only disadvantage is, as I said, the cost.
I'd put 'em in ... YOu can adjust chargng a tenth of a volt or two if you have to.