WILL, I know you are experienced dev and all, but that control scheme is AWFUL!

IMO, it should be as follow:

L2/R2 - prev/next weapon
L1 - shoot
R1 - Mine

Y - Throw clip
O - Toggle dive

Reasons:

Shooting is in games pretty common action, as dropping mines is. Buttons used for this should be available for players without getting away to much. Also using index fingers for changing weapons and shooting/placing mines is pretty straightforward and easy to get.

Putting away clips isn't good thing in most cases, so it should be assigned to button where player is actually 100% sure that he want to do this, so he won't throw clip accidentally, therefore Y.

Dive is not as rare action as putting away clip is, but isn't as common as shooting/placing mines, therefore it should be assigned to accessible key like O.

For right stick I'd propose aiming (left would be for movement).