The gap or lag between preset changes was pretty disappointing for me as well. I'm not sure if it's the dry signal coming through (while in killdry) or just the sound of the algorithm and parameters changing that causes a phasing sound but I hear it too.

What has worked well for me is just using CC messages to change the mix and decay of a Space preset when changing full rig presets. So when I go from a Fenderish clean to a Marshally crunch with a preset like "Guitar Room" I'm just lowering the the effect mix and decay Via CC. This way there is no glitch whatsoever. Yes, it is a compromise but it does work well and sounds very natural. I just hope your midi controller can send multiple CC messages!