If you can ride correctly with two reins then the bit acts exactly as a snaffle, the curb only comes into play if you want it to and to the degree that you want it to.
Serenity, I know you from old and we haven't spoken for years on here, you'll know from my user name who I am. Our boy was 4th at HOYS last year in the ladies hunter so I do think that I have some substance to my response, a sliphead is absolutely not 'correct' for showing. It's correct if you...