I think I'd prefer to see year sets for Mercs and some other early 20th century sets - just one coin for each year of production. A Denver set of Mercs would lack a coin from 1923 & 1930, and a San Francisco set would be missing the 1921 and 1934. If you carry the same principle over to Walkers, there'd be a large gap in the P mint coins between 1921 and 1934, and only one D mint coin.
A complete mint state year set of Lincolns or Buffalo nickels wouldn't be beyond the reach of many Registry participants, but several series would have at a "stopper" in mint state - any 1921 dime, a 1916 Standing Liberty, and the 1921 Walkers - but that would make it all the more challenging. It would probably also increase the demand for the more readily available dates.
Comments
A complete mint state year set of Lincolns or Buffalo nickels wouldn't be beyond the reach of many Registry participants, but several series would have at a "stopper" in mint state - any 1921 dime, a 1916 Standing Liberty, and the 1921 Walkers - but that would make it all the more challenging. It would probably also increase the demand for the more readily available dates.
Jim