See I would probably think a myler.
Kimblewick we have always used for hunting if a snaffle fails. If the Kimblewick fails they get moved into either a pelham or gag.
We have one in a cheltenham gag and he is not really that strong but every now and again has ideas above his station and I find it great as it is pretty gentle till you need it to kick into action. I would have thought a continental gag was stronger as even the slightest touch brings it into action which it does not do on a cheltenham. I am guessing the next step up from a continental would be american?
I find vulcanite pelhams pretty soft and kind bits in the right hands.
From the different answers coming from various people not many peopl,e are aware of the strength of the bits they are using. I believe that if you have a problem re biting You need to speak to an expert who will give you the definative answer. If you don't you end up, like alot of us, with a drawer full of nearly new bits that we've accumulated over the years but will never use.
Heather on this site is very knowledgable:-
I agree the experts are often the best port of call, however, theory doesnt always equal the result you want, horses are all individual, and just because a bit is meant to do one thing, doesnt necessarily mean the horse will react to it to cause that thing to happen. I have consulted several "experts" in the time of having horses, and they have all been massively helpful, but the horse won't always react in the way it is "meant" to. Thats where other peoples experiences with different types of horses in different situations come in helpful (eg this forum).
So answering the original post, the mechanics of one bit can make it stronger than the others in theory, but depending on what the horse is sensitive too, and what presses the right buttons for them, will decide the severity in that particular case! Hope that makes sense
Also worth noting that if you call Heather at Neue Schule, she is going to recommend Neue schule bits.
Whilst they are nice bits, they are not the be all and end all. There are plenty of cheaper lozenged bits out there that offer similar ergonomic action at a fraction of her prices!