Well, colour me surprised, and apologies for previous scepticism. I'm guessing you won't be making any more announcements on April the 1st

If you make another iteration of it with a swappable battery I'd definitely consider it. I'm not sure there are any out there - I think it'd be a really good "unique selling point" - and the counterarguments (e.g. thickness, loss of waterproofing) don't really seem to stack up for tablets (personally I'd argue they don't stack up for phones either, but hey...). Even if it were held together with screws or similar, rather than 'user swappable' in the obvious sense, it'd be a big improvement.

Good luck with the project!