The Hybrid Zukertort Retort
I have posted analysis of what I call The Hybrid Zukertort Retort (1.d4 Nf6 2.Nf3 d5 3.e3 e6 4.Bd3 c5 5.b3 Nbd7 6.O-O Bd6 7.Bb2 Qc7!?), which is a surprisingly playable Black system against the Colle-Zukertort. I analyzed the line after reading David Rudel's excellent Zuke 'Em: The Colle-Zukertort Revolutionized, which I will soon be reviewing. I discussed the analysis with Rudel himself, as I acknowledge in my notes, and he has agreed to an interview (which will be up later this week). Rudel maintains a great website on the Zukertort at www.zukertort.com which I recommend to you if you are looking for more information on his book or the system he recommends.
I took a close look at this line because it seemed a principled retort to the Zukertort, fighting White for control of the critical c4 and e5 squares. Rudel discusses this line in Chapter 11 and again in Chapter 12 of his book, calling it "the Hybrid Zukertort" because "Black combines the Classical line with the Bogolyubov by putting the Knight on d7 and the Bishop on d6" (231). I think the critical idea also involves playing Qc7 (which Rudel and most previous writers think is dubious) and delaying castling in order to gain a tempo for pushing forward in the center. With Qc7, Black simultaneously threatens two potentially equalizing pawn advances with c4 and e5. The c4 advance is actually not so critical (though it seems to gain enough space on the queenside to claim equality), but if Black can win control of e5 and play the e5 pawn push then he has basically dismantled the cornerstone of the Zukertort strategy. A couple of drawn GM games suggest that this method might squelch any White initiative and close analysis mostly supports that conclusion--though White has a few options to explore in search of an edge (especially in the lines following 8.Nbd2).