I haven't been following Heighway that closely until recently, but man, I like everything I'm seeing/hearing. Alien in particular sounds like it could be pretty great. Can't wait for the reveal.
As someone with limited space, I really like the swappable game concept. I've been following the P3 for the same reason (plus it has some other cool features and a ton of potential in general). I think their swaps are actually even faster, depending on how many different modules you have to swap for a given game (just back of playfield, or others like the flipper area too). But that looks pretty slick for a full playfield swap! Even if you go a bit slower, <5 minutes is short enough to swap it on an impulse, or in the middle of a get-together.
I could see potentially buying into both of these systems and having way more games available than I'd otherwise have space for.