I very much like this idea, but unless a coin is worth 1 million then that is still way too many numbers for:
Idiots- (yes mean but we all know them), average joes, older persons(not all), and electronically handicapped(mother) will still have difficulties and they account for a big number of the population currently.
No it will be fine. Humans are far better with big whole numbers like 10,000 than small decimals like 0.0001. Italian lira and Chinese Yen are a couple of examples, I'm sure they have their fair share of 'dumb' people in these countries