playBunny: and even some games (I guess what you might call standard games) at World Class level. This is something that any of the top 50(?) players here is capable of.

Reduce approximatelly 45 from 50 and you are OK....
I guess that the first 50 are on the Intermediate to Advanced in the GNUBG grades.....That's mainly because almost all here play too defensively by not leaving any blots.
(A small example: I've seen millions of times to play the starting 41 as a 5, you know where. Awful!) This is not a terrible strategy, its quite successful(although compared to the best strategy is far behind), but that combined with other weaknesses, it's way below the GNUBG's Expert level............

Also do not always trust the Snowie's or GNUBG's or Jellyfish's or BGBlitz's (you forgot that and it's really strong!) estimates of your play.
For example the usual thing with me is that GNUBG finds around 3 small (Second choices or ?! if you are familiar with GNUBG's analysis) mistakes on a game, but after a rollout, the 2 of them are actually the best moves.........So you should always do a rollout in the identified mistakes......

Also Jellyfish 3.5 as a player !!in its full strenth!! but without any analysing features, is free and very small to download and play with a very good player......

Right now i would rank as following:
1) GNUBG 0.14.3 with very little difference from
2) Top Human Players + Snowie 4.1
3) BGBlitz 1.9.0
4) Jellyfish 3.5