To be even more fair, at the time the Redfield coins were slabbed the ONLY people using the "Sheldon grading numbers were the EACer and Paramount. Everyone else were using Unc, BU and Gem BU. The Redfield coins were circa 1974, and the first grading guide to use the Sheldon Numbers was the ANA guide that came out in 1977, and then the first grading Service (Accugrade ) in 1984, and then PCGS in 1986. It really isn't fair to criticize a firm for not grading to a standard that didn't exist until 12 years later. That is probably fairly accurate.
Just my opinion, but I think our current Sheldon grading system is fine today, what ain't broke, don't fix it. Thats what + designations are good for. I also think NGX's attempt of remarketing grades is stupid. It's good for the TPG's pocketbooks though, when all of those bizarro slabs are submitted for crossovers.