Ok, a White cathode follower (more of a push-pull). I haven't really looked into using them. Although, it seems you might be able to implement one using a CORNET. The difference is that I use a BJT for the current sink. I think Allen Wright uses something like this.
In general, adding tubes is costly. Depends if you are designing bang-for-buck or state-of-art. When you can throw money at a project, that's one thing. Making a CORNET sing is another. That's where compromises come into play. Add a tube, and you need more chassis space, more circuit board, more heater current, etc. There is quite a ripple effect. That's why I always design from a system viewpoint.
But back to the White, I don't have much to say as I've never tried one. It looks fine from a theoretical standpoint. You might have to watch out for power up issues.
jh
