The rulebooks say not to do it, but I can tell you from experience that it works fine. Might be different with mechanical systems, but the power from a Di2 or eTap motor is more than sufficient to hoik it up a big jump like that.
It's not the cleanest shift in the world, but it does work.
Fair enough, but like... you’re wrong.
I ran 52/34 - 11-28 in Spain and it fucking ruled for long climbs.