Sometimes for me modularity is a good thing -- for instance, on the AP EOT, if I understand correctly the wonderful complications are all mounted atop the splendid 2120 ultra-thin automatic base movement. (I could be wrong here, in which case I will happily stand corrected!).
For me it's almost like getting two great movements for the price of one -- the 2120 is so acclaimed that it's a treat to have, and the EOT stack on top is, to me, a marvel as well.
And (perhaps unlike with chronos for some people?) given that the interface is simply about the transfer of power, I find it difficult to believe that there's any substantial performance loss relative to a fully integral design.
All for now,
Gary