I don't have an answer, but I've been thinking about it. A print developer formulated with benzotriazole as its only restrainer sounds doable, but how will it respond after some paper has passed through it? Bromide will be released when developing paper, since nearly all papers have silver bromide. So, it seems that, inevitably, print tone will change to warmer tones rather quickly. On the other hand, if both benzotriazole and KBr are used as restrainers, the released bromide will be, for the most part, a small amount of the bromide already present in the solution, so print tone will be stable after more prints have been developed in the solution.
Can anyone comment on this?