I would just make one block with boost and delay assigned, and a second block with just delay on it. There would be no issue with slow switching between presets because you would working in one preset... no need for switching in this case. If it is a super busy/involved preset and you are trying to save every last bit of real estate then understandable why you wouldn't want to have to add a second delay but if that's not the case, you're better off just adding a second delay block independent of the boost/delay multiple.