BSMS Thanks I was just thinking the same thing.
I'm torn with waterfords and chain bits. They're wonderful because they completely conform to the horse's mouth with no nutcracker action. They're practically nothing in a horse's mouth when not being touched. But when 'in action' they can be very pinchy, Waterfords and chain bits both centralize the pressure onto a number of small points, chains having smaller edges, so my thinking would be slightly more intense. But Waterfords have the lumps for pressure points.
Having nothing solid, there is nothing solid for a horse to brace against, but I'd attempt using a loose ring french link before a waterford. The loose ring makes it more difficult to brace against too. I'd also probably try to find what's causing this behavior in the horse before just making the bit more difficult for them. Bit changes are often band-aids in that sense, not fixing the actual problem, just the symptoms of the problem.
I'm curious to hear more opinions on the positives and negatives of chains and waterfords.
One other bit I'm greatly interested in are those all leather bits?! It has the same idea of waterfords and chains, where it's got no solid form, just conforms to the horse's mouth. But it has no joints or pressure points to increase the strength. I feel it'd only work well for a well trained horse. Kind of like the flexible rubber ones but don't get sharp edges if chewed a little.