if you have 66 not 44 this is a totally different discussion
And much more interesting...
This imo. Means we actually have the nut draw and not so important that betting isnt closed. With middle set, we have some of our own outs to what we think will be the best hand, but a 6 could technically lose us the pot if the guy behind has a 2 pair combo.
Think its pretty close with top set. I might still fold... He can only have the nuts/second nuts and we are drawing. With top set and the blocker we have 6 outs to make the effective nuts (and running pairups), whereas with middle set we only have 3 if they have top set/2 pair (and only running 22/55)
Again, I may be wrong
