And in my experience, A3 (16x11) is my standard large print. And 35mm film easily gives excellent results for this size.
24Mp digital gives you about 375ppi at that size. My 35mm scans give me roughly 200ppi (13Mp) on a Plustek 8100.
The issue we're having is likely to be nose-up-close examination (as you mention 100%). If you assume a normal viewing distance of an A3 print to be 30 inches(?) the human eye (assuming 20/20 vision) cannot resolve better than 115ppi. It's only when you get to 12" distance that the eye may be able to resolve the difference. Certainly my eyes can't as I don't have 20/20 vision (and I've tried it!). The only step closer than that is zoomed in on a computer screen at greater magnification than the eye can see at.
And discussing the usefulness of looking at images at 100% is a whole 'nother conversation