Roscoe:

I think yes and no. I'm not at all convinced that "modern" steel has ameliorated this problem. Min wall thickness seems to remain the critical issue. New doubles built with traditional barrel profiles have been damaged by monos. Doubles with thicker barrels will obviously be more resistant to such damage, perhaps even entirely resistant to it if thick enough, but there are no freebies. The concomitant penalty such rifles suffer in weight distribution/handling dynamics eliminates them from consideration for my own personal use. I handled a new German built .450/.400 in Reno that looked like you could shoot solid steel through it with no damage, but what a railroad tie it was! That said, as you're aware, I've been accused of being rather picky about such things though.

TBBC has a homogenous shank, and thus presents the same potential issues as any other mono.