I use a T3 with a Cookie Flat Lock mount and it is a pain sometimes to get into the card/battery. I typically just loosen the mounting screw enough to rotate the plate 180 degrees at which point I can open the slot and remove the card. I've just gotten around the issue by using larger cards so I rarely have to dump my cards until the end of the day.
Steeper trim, longer lines. I've jumped several with this setup and in my experience they tend to dive a little longer, and gives em a little more range on rears. It also in my opinion, helps with the openings tremendously. I own three FX's with JVX lines (minus a2 and c2) and absolutely love them this way.