Geometry question: shorter stack with same reach?
Don't just look at the stack and BB drop, consider the steering geometry as a whole (chainstay length, BB drop, head angle, front-center [BB axis to front wheel axis]) which will affect how the bike handles; and the cockpit geometry (stack and reach) which will affect your position. Cockpit geometry and steering geometry are interrelated obviously, a bike with a long front-center will have a long reach for instance.

The Grade geometry is really long chainstays, long front-center and a slack head angle (FYI, I own one). The stack is quite high too. If the CX frame you are looking for has a very high 57mm BB drop I bet it has traditional CX race steering geometry as well: short wheelbase and steepish head angle. You'll very definitely feel a big difference between the Grade and and a trad CX frame like that.  

I'd really hesitate to use a race geometry CX bike for touring. The high BB moves your center of mass higher up and the short frame and steep head angle make for quick steering - not what you want for loaded touring. I don't think you'll want a low stack that results in a leant-forward rinding position for long days in the saddle either.

There are plenty of gravel frames out there that are shorter, have 1/2 degree steeper head angle and a little less stack than the Grade. That's what I'd look for for a touring adventure/gravel bike.

BTW you don't need a high BB for 650b wheels, as the point of using those is to run larger tires (45mm+) than you can with 700c rims. The difference in whole wheel diameter between a 700c with 25mm tires and 650b with 45mm tires ends up being quite small.