Typecoin:
First, not all the coins are strictly conditional rarities only. I think most folks would agree that a 1912-S
Liberty nickel is a key date, even if it is charted at the top. A 1945-S
Walking Liberty half is certainly at the top end of the grade scale at 67, but I'm not sure I'd call that "only" a conditional" rarity. Yes, he is using the high end of the scale as comparison on all the coins, but that would be the LEAST likely grades for such huge increases in such a short time.
Second, you said that his benchmark was 5 years. Actually, if you READ the charts (forgetting months, just years)there was: 1-8 Year, 2-5 Year, 3-3 Year, and 3-2 Year comparisons.
You and I are usually on the same page on most things, TypeCoin, but I think your zeal against
TPG's in general biased your opinion. You are usually pretty good at listening with an open mind.
The majority of coins I purchase are in a price range where I'm simply an idiot if I don't purchase them in NGC or PCGS holders. Especially considering that the prices for raw and
TPG'd coins in those price ranges usually have little if any difference. So I'm usually not paying any more for the NGC or PCGS than I would for the same quality coin without their opinion.
In the last three years, particularly, I've been FORCED to buy more NGC coins than I have in the past.
I do keep track. In 2012 my purchases were 67% PCGS, 33% NGC, in 2013 my purchases were 58% PCGS, 42% NGC, in 2014 my purchases were 51% PCGS and 49% NGC, in 2015 my purchases were 47% PCGS and 53% NGC, and last year my purchases were 31% PCGS and 69% NGC.
So for myself, I've really turned more toward NGC for the simple reason that I DO buy the coin and not the holder. Most of the coins on my want list I have to look at dozens or even hundred of times for the same date and mint mark before I find one that meets my needs in eye appeal, grade, and price.
ALL OF the coins I've sold in the last two years have been PCGS. I haven't sold a single NGC, because I didn't have any I wanted to sell. In looking at some of the PCGS I bought recently, I see that I might have jumped too quickly on "filling the hole".
I've been to enough shows, both small and large, to get a good feel of what collectors, dealers, buyers, and sellers are feeling right now, and I can tell you that I've listened to some pretty "religious" spiels against PCGS on more than one occasion.
I was at the table of one dealer who was being offered a couple dozen nice medium grade (EF-AU) Bust Half Dollars in PCGS holders, and he was having a VERY rough time. Those are coins that usually have way more buyers than sellers. The dealer he presented them to said he would have to crack them and submit them to NGC before he could sell them. Maybe a "reason" for a lower offer, but I don't think so. He had about 12-15 Bust Halves which were all in NGC holders.
You can all decide for yourself by voting with your money, and while "buy the coin" will always be the rant shouted ad nauseum, sometimes the influence of a
TPG grade should be entirely disregarded.
From my own experience I know I'm buying a lot more NGC coins simply because they meet my needs better.
I could start on classic silver commemoratives, but I've yammered way too long...