Anthony, I just watched the video from Simon Williams you posted in #21. Amazing - that is the game I have been referencing this whole time! :-) Like playing against From's Gambit, I think if Black knows his stuff, he can walk out of this variation (4. e4) with a playable position. I believe 4. e3 is playable, but encourages Black to work on his pawn-roller he has already begun. I have read two players (both stronger than me) question 4. e4, but my question is - what type of pressure does e3 put on Black? Sure, it stifles ...f5-f4, but that isn't the end of the world. ...f5 as a move does more than just threaten to crack the kingside. It fights for e4. And later, if Black can castle queenside (there is a nice win for Black in the database after 4. e3), he can push ...g5-g4, and even gambit a pawn or two to crack the kingside if necessary.
Maybe we could propose a Hopton Attack tourney? 1. d4 f5 2. Bg5...
Ozzie, I agree with what you have written - there are many authors who try to force lines. Even some of the lines in Taylor's Bird's Opening book I have to take a grain of salt with...even lines in many different books. But the ...d5 approach is a solid answer to White's response against Black. I am not saying it is to every player's taste, but it works for me - it gives Black a chunk of space in the center, with room for maneuvering.
I do think a Dutch player must have a good answer to 2. e4, 2. Bg5 and 2. g4. Anything else gives him time to develop normally.