I don't like the idea of switching lists with your opponent, as different people build lists specifically branded to their strategy and how they like to play. For instance, some people hate playing swarm lists, don't find them fun at all. Switching lists could negatively impact those people.
A Mini escalation sounds kinda fun and I'd be up for something like that. I also see the benefit of bringing two lists, it almost serves the function of a Side Deck, though I'd rather see something like a "core" 60+ points, and then up to 40 additional points, and you can have 2 sets of that up to 40 additional that you can swap out. Neither list option is allowed more than 100 points in that case of course.
Personally, I've been trying to figure out ways to add objectives to competitive games that would change the meta and gameplay without overtly favoring one strategy. I'd rather do something like that than mess with people's lists too much. Scenario Design is what's keeping 40k alive right now, and there's something to be said for that, and worth looking into for designing fun new ways to compete.
All in all though I very much enjoy vanilla tournaments, and as Brian pointed out they're a way to get us ready for the big tournaments. Throwing new things into the mix would mess with that a bit, and it's not like there's a balance issue we're fighting. I do have some cool ideas developing for off-nights, and I think that's where the crazy new things should go. I wouldn't mind playing alternate format tourneys on the off-weeks at all! Not every off-week (other fun things we could do, like throw an imperial corvette against a tantive), but once every month or so kind of thing.
EDIT: There are official rules for Epic Dogfight tournaments on the FFG website. I'm not sure how many people would have the ability to run that many points, but we could run a team epic tournament (5 Epic Points per team, 150 points per player) some week. I'd be all for that!