I'd prefer a boxed edition of any game over a download but....I don't need/want any extras & I'd prefer a download anytime to a disc version that comes with the need to set up e.g. a Steam account etc as has just happened to me with the disc version of Chaos on Deponia which I later saw I could get on GoG
(I might aswell use the disc as a frisby as it's absolutely worthless - I just don't need it!)
My thought is to release the game as digital download & if it does well enough could you not release a disc version later (without the need for Kickstarter?) - that seems to be the way at the mo?