Interesting, I may make an account there.
Now that I look, I see a rating of ~2000 gets you on the top 20 rankings for that site.
I wonder what sort of problems FMs (and up) are able to solve in 3 seconds... probably pretty humbling.
I think Shirov had an account on there some years ago, and his rating was 2300-2400-ish. It's hella hard, that's for sure, and it is very easy to dump a couple of hundred points on any given day.
The memorization angle that you mention is interesting, especially that you have a friend who can solve problems quickly, presumable due to memorization, but his tactical ability doesn't tranfser to playing ability. It's interesting because memorization is exactly the method recommended by GM Ziatdinov, just get exposure to many patterns that you can recognize quickly.
Let's keep distinctions clear: does he recommend memorization of particulars or universals/generalizations. I am guess he emphasizes the latter, though he may be speaking generally enough for one to take him to mean that individual (i.e., particular) puzzles should be memorized. People who memorize particular puzzles have not necessarily assimilated the pattern. I am definitely all for memorization, but of this more general type. Memorizing particular things doesn't help much, except to aid in developing pattern recognition a bit. That's why studying many puzzles with the same motif is more effective than memorizing one particular puzzle within a motif. It is also why Dan Heisman advocates something like the de la Maza method, except much more systematic, in that he suggests we be able to do every basic motif type (in a selection of books he's pointed out on his website) very quickly.