I agree that SMW probably couldn't be used by itself for this, and that Semantic Forms makes more sense. Thankfully, though, I don't need to create a proof of concept for this opinion, because one already exists. :) In 2011, Christoph Tempich created this demo, showing how Semantic Forms - and specifically the #autoedit function - in conjunction with some clever Javascript, can be used to create an editable table:


Double-click on a cell within the second table, and be amazed. :)

I've sent this link to the mailing list several times, by the way. as part of different threads, but for some reason it has yet to really make an impact. Still, I think Christoph's solution could be useful for a lot of cases.