Beau--Slightly OT... But do you recommend this for English bit/bridle gag combinations as well?
Are you referring to the bit guards?
If so, YES.
A gag bit is a gag bit, no matter what discipline you ride. That mouthpiece can slide, and has the potential to pinch skin.
Even my colt that I ride in an O-ring snaffle bit has bit guards. It's not a gag bit, but that ring can still slide around on the mouthpiece, again, giving the potential to pinch.
At least that's my opinion, anyway.
Out of curiosity, what difference does a straighter shank make?
A straighter shank gives you a quicker signal.
For example, this bit could be considered "harsher" because the shanks are straighter. The very instant you pick up on the reins, the horse is going to get a signal because the bit will engage.
Versus a bit like this, where the shanks are "swept back". This bit could be considered a little more "mild" because the horse is going to feel you pick up on the reins BEFORE the bit itself is engaged. It gives the horse more of a warning.