Hi
I am going through the exact same thing with my ex racer and have had some lessons with an experienced instructor to help me.
I think it is important to look at the action from the ground. If there is any kind of evasion, incorrectness of going, any odd head carriage.
Think also of the mouth shape, tongue size, natural tendancies (head up,head down)
This is all very important information.
You don't say if there are any problems as such, i.e. objection to nut cracker action.
I am very impressed with the waterford (don't shoot me down guys!) I know it is a controversial bit, but my boy has a large tongue and small mouth, so therefore he gets upset if his tongue is squashed, and I like the waterford as it sits nicely without pressure and he mouths the bit nicely, which he won't do in a link or snaffle.
I am not at the end of my bit journey, rather the beginning, I am aiming to down grade on bit once I get correctness of head carriage and a stiller ride, sometimes you will need to change to something as a means to an end to help schooling correctly and then work back down the bit scale.
I hope that this gives some food for thought x