That has been the main reason that I haven't even looked at bamboo ferruled rods. In fact, I worry about it to some extent even with metal ferruled ones. I pulled a ferrule off one of my favorite rods last week after an afternoon of doing mostly double spey casts. The ferrules weren't particularly tight fitting, either. At least I reset that ferrule easily enough; integrated bamboo ferrules would destroy the rod if broken.When my friend gave me the Savli as a gift, James Reid, who makes splice jointed, hollow single and double handed rods, expressed concern whether a bamboo ferruled rod would be suitable for performing any spey cast where there is a large change in direction, and also "sustained anchor" casts such as a Double Spey, Circle Spey, Snap-T as he didn't believe the bamboo ferrule could withstand the lateral forces involved in making such a cast.
I'd add Belgian casts into the high-stress category as well.