My initial impression of the big table was very positive - for a start I like the graphics. But then I noticed problems. For a start, it doesn't include "half" relations, except for on mention of half-siblings.
It also says that you share siblings share 3/8 of their DNA, when it's really 50%. The problem is that the cM match calculation isn't a straight % of DNA match, at least not for your very close relations and they have jiggered the shared DNA percentage to match it. When they calculate cMs between you and one of your parents, it comes out near 3400cM because that's a 100% match - they look at both sides of the chromosome and if EITHER matches it counts as a match. Since mom is always on one side or the other, she matches at EVERY location on the chromosome - same for dad. If you did a match against YOURSELF (or a identical twin) you would get the exact same result. You get a 3/4 match with a sibling even though you only have 1/2 the same DNA because there's only a one-in-four chance that NEITHER your DNA from your dad NOR your DNA from your mom matches at a given point on the chromosome. But beyond that, the % actually tracks the cMs. It's a little tricky.
But the calculations they do for about 3C and beyond are meaningless anyway, because they ignore that DNA is inherited in segments. So most of the numbers given are total junk.
Still, I got excited by that blurb in the upper right, which gives info that I had been wondering about. But then I noticed that the info is apparently WRONG. When I look at what it says about 2C, it says they run from 193.8cM to 343.72cM. Half of my own 2C results (AncestryDNA) were below 193 - they go as low as 102! Even Blaine's useful but problematic chart says it goes down to 46cm. I have 2C1R and 3C results that go lower than what they say too.
I've been interested in at what point you will ALWAYS get a match, though, so that part seems interesting and is probably correct. My quandry is that have two matches who I'm pretty sure must be 2C to each other (3C to me), but the Shared Matches list for them say they don't match each other. I know for sure where the one fits on my tree, but not the other (although there things about him that give me a really good idea). It's very puzzling, and he hasn't answered my query.
My brother and I both have the exact same matches up through 2C1R, so I had the impression at one point that that was 100%, but I think I've also seen cases where 2C1Rs didn't, so maybe they're right.
The 89.7% chance of a match for 3C sounds reasonable to me. Both my brother and I match 86% of our 3Cs that I've been able to find are "out there". If I identify some more 3Cs within our matches, my number could go up. But I only know about matches from three places (1) my matches (2) his matches and (3) DNA Circles - so there could also be 3Cs out there that I don't know about, and that would make it go the other way. I don't have enough data of my own to comment on the 4C percentage, but what they have seems reasonable.
I've criticized Blaine's famous table before. Basically, his data analysis is lacking. He includes the endogamous data, which greatly inflates the max numbers (endogamy makes them virtually unlimited). With the distributions being asymmetric, and using the endogamous data, the averages are way too high (they're practically max numbers, for non-endogamous). I don't like the data presentation, with the "halfs" over on the left, and since there are really just "classes" it really doesn't even need to be a 2D table anyway. Oh, and the results are somewhat different for different testing companies, but they're lumped together into one anyway. This is our "Gospel". Sad. Still, it's better than nothing, and I applaud the effort. I'm just saying it's a shame he didn't present it more usefully.
I'd like some real numbers for what's really going on, so that why I've done my own analysis of my own data.