One of the finest numismatists of the 20th and 21st century is quite accurate. He's posted on another forum within the last 72 hours as ProofArtWorkonCircs.
I often call him the very first clad quarter collector though, of course, he's far more. Like me he tracked these coins from 1965 but he was collecting them from the beginning and I didn't start until 1972 when the mint began rotating their coin stocks. RS Yeoman was talking about the coins by 1968 and John J Pittman began collecting them about the same time I believe. No doubt there are others but of the many collectors of clad I've encountered over the decades most started in 1980 or later. There was an influx in 1999 as well.
He was the first collector to write articles about the different types of reverses on the early clad quarters and popularized the type b reverses on the '56 to '64 quarters.
I'll send him a link to the thread.
Time don't fly, it bounds and leaps.