I hate to use crappy digital terms (honestly, I hate digital), but in raw scanning terms, 4x5@4kdpi is over 300 megapixels and 8x10 is in the gigapixel zone. These are way beyond anything purchasable today with reasonable amounts of money. "Old" technology once again wins here. Cost-wise, medium format digital backs approaching 50-60MP are like 20 grand. Do the math (and then remind yourself it's not all about math because analog is a non-linear medium).
Stop worrying about grain, resolution, sharpness, and everything else that doesn't have a damn thing to do with substance.