This is exactly what I was thinking. It seems crazy to roll this out instead of parse until there's a very clear reason why - and it's actually going to be more fun to use parse anyway since you get away from this kind of stuff.
On top of that, building this out is unlikely to match much of parse's capabilities unless a huge amount of work is put in (by you). And once it's 'done', it will no longer have that magical property of getting better without more work on your part, whereas Parse will continue to grow and kick (even more) ass.
There's almost certainly some part of this approach that would be fun, but I can't really think of it off the top of my head.
with apologies to patio11 for (mis)appropriating his meme.