This is the reality of how sound works. The size of the sections and how loud they play will effect the amount of air moving in a room which will literally reflect how much reverberation will happen. 3 players playing at piano is quieter and move less air than 6 players thus you get a sense of a more intimate or in your case, "dryer," sound. There are many ways to compensate for this like asking the smaller sections to play their dynamics louder than written to match that of the larger sections but then you lose the realistic expectations of what a true pianissimo or fortissimo really is with an ensemble of that size.Back to the actual library, I had another listen to the walkthroughs. Maybe its just my ears, but the Divisi sounds drier, like its using close Mics only compared to the full section.
Is it just me, or have they employed the same technique Hollywood Strings did to get Divisi?
I haven't asked @Strezov as to how they recorded the divisi but my guess, having been working with the library for a while now, is that the half sections were the front desks and the full ensemble includes the desks further back. This would make sense in that you hear what sounds like a closer sound since only the front section is playing. I hope that all makes sense.