Considering I mostly have at least 1 reverb loaded at all times, this workaround sounds like something that would fit my play style (allowing me to switch on the fly with one button). I also love the idea of the bypass toggle acting as a kill switch for everything. A lot of huge damp reverb tremolo parts with massive drops into a quiet moments that could really be done much easier with one button - that's exciting.
I'll have to look into Snapshots. Haven't gotten that deep just yet. Though, all in all - I'd honestly love to suggest some sort of ability to turn off effects when another is selected (as you mentioned - close to M13 style workings). If we were able to register effects into a "Group" of some sort, where the system knows only 1 effect of the group could be selected at a time... it would literally solve everything! Seems simple enough.
As for Split A/B, I'll have to consider that as well ! I've been mostly using A/B to run parallel effect chains - which has been one of my favorite parts about the Helix so far. Now once I figure out how to write in a blend to the expression pedal... Dream.