I’d actually take 2.5” plain edge, and a full inch of serrated. Anything less, and the serrations are useless to me in most cases.
It’s funny you mention a Gerber MT. The blade on my Crucial is exactly why I dislike small combo edges. At less than 2”, there just isn’t enough edge for both. The serrations are almost a full inch, which is useful for most tasks, but the plain edge is just to short to really do much of anything useful in a working environment. I know the Crucial is a bit of a compromise itself as MT’s go...