Hi,
Given that the filters (including the 850/900) are all unbalanced-to-balanced filters, I doubt that somebody would simply not place them (as you cannot replace them just with a 0ohms resistor or soemthing. By removing one filter you would not be able to produce a standard 850/1800/1900 or 950/1800/1900 configuration but something like 850/900/1800 or 850/900/1900 which doesn't maeke sense.
Have you noticed that the capacitors on the 850 path are marked as N/C ?
I don't see why they wouldn't have put them tough ... it's not like it changes the price much.
Sylvain