* * DA Anyone have a preference on Concorde vs. Gill?

Yes. I've used both a Gill and Concorde in my Aircoupe and the
Concorde outperforms the Gill. *I'll never buy a Gill again, they
don't last.
--
The church tries to save sinners, but science seeks to stop their
manufacture.
*~ Elbert Hubbard

I'll second that - The Concordes are noticeably better.

I haven't tried an AGM Aviation battery, but recently had a bad
experience buying some AGMs for an electric scooter. Turns out the
brand new "Deep Cycle" AGMs were not even equal to the worst of the
batteries I was replacing (same size/shape/AH rating, but a different
brand that appear to be unavailable in the US).

David Johnson