Manhattan GMAT is in process of reviewing their books... & I think they they'll or might have already publish(ed ) new set of Manhattan GMAT books...
I heard that it was going to off on April 2007... so dont know if its already in the market or not....
Still not that you asked for suggestions.. O
I would keep Manhattan SC 2003 ed book. ( & wont purchase newer edition)
since Grammar never changes...
and as for the OG 11 & Og10 is concerned I think they are well classified books in the explanations they precisely have given which question belongs to which category...
SO it would be easy to you to classify the problem like they did in MGMAT SC book for OG 10. c'mon it's not a meticulous job (as compared to other GMAT planning

)
Hope that helps
Attention: I think
Even if they come up with new version for Manhattan SC I dont think they'd change the content much... since the earlier book was superhit...
they are changing the content for CR & RC though... making it two separate books...