I built a preset last night using two amps and a dual cab. Snapshot 1 has one amp on, snapshot 2 turns that amp off the second amp on and changes the cab parameters, specifically mic type, distance, positions and angle. When switching between snapshots there is a delay and a gap in sound. It's very obvious when going from gain to clean sound but still noticeable switching between two different clean amps.
Keeping the parameters exactly the same on the cab block is a seamless transition so the problem appears to be a delay or gab when switching the cab block parameters.
I'm working on making a video showing this also going to test this with one amp using different drive settings per snapshot and different cab parameters.