Two days ago I finally received my copy of Schmücker's 'Das London-System'. I have not had time to look at it in any detail and will not have for a few weeks, but here are a few quick observations:
The cover illustration is nice but otherwise the book's lay-out appears rather amateurish: the pages look a lot like ChessBase print-outs; all variations are in square brackets; there are no chapter headings (except for the headers - together with the page numbers) and frequently there are no introductions to the chapters (at first you have to wonder why the right-hand side columns on pages 44 and 95 are empty; then you discover that there actually start new chapters on the next pages).
There seem to have crept in some typos - a rather visible one is diagram 174 which shows the initial position whereas the text indicates that it should show the position after 2.Nf3 Nf6 3.Bf4 Bf5 4.c4 c6. There also are a few misspelled names. More importantly I wouldn't expect there to be any illegal or very poor moves as ChessBase would prevent this.
The main question of course is the quality of the chess content; the analysis, the research work and the textual explanations. I cannot really say much about his analysis yet, but it seems he has caught at least one serious omission in our London book. Except for a 2007 game by the author I couldn't find many recent (2005-2007) game references. I saw a 2006 reference and I probably have missed some more. Nevertheless my guess it that the manuscript were mostly done in 2005 and after that has only been spot wise updated. Schmücker's textual explanations appear sufficient and generally clear enough even though he hasn't bothered much with making complete sentences.
A main point of divergence between ours and Schmücker's recommended repertoire seems to be the line 1.d4 d5 2.Nf3 Nf6 3.Bf4 c5 4.e3 Nc6 5.c3 Qb6 6.Qb3 c4, where we suggests 7.Qc2 (or avoiding the line completely with the 2.Bf4 move-order) whereas Schmücker recommends 7.Qxb6 axb6 8.Na3 (Dia)
For our London book we too had originally planned a chapter on this line. However, when space limitations became an issue it was among the first lines we sacrificed - mainly because we were unable to demonstrate any advantage after 8...e6 9.Nb5. When 8...Ra5 too proved a tough obstacle, and 8...e5!?, 8...Rxa3!? 8...Na7 and 8...Ne4 each required rather deep analysis and corresponding space, simply skipping the line seemed an obvious decision. Schmücker provides extensive analysis of 8...e5, 8...Rxa3, 8...Bg4, 8...Na7 and 8...Ra5. I don't now why he doesn't mention 8...Ne4?! as the refutation is rather instructive. As for the quality of his analysis I can only guess but he obviously must have put a lot of work into it so probably it's quite good.
The big surprise is that Schmücker proposes to meet 8...e6 with the untested and modest looking 9.Nc2!?. Can this really be sufficient to fight for an advantage? I will not completely rule it out; Black has as Schmücker points out locked in his light-squared bishop and White can fairly easily neutralize Black's play in the a-file. Pure analysis isn't likely to reveal much in this quiet position so I hope to see some practical examples soon.