Eh? I think we're working off different definitions of darkNXT!

 - NXT that is in an account that nobody knows the passphrase of == darkNXT
 - NXT that is in an account that hasn't yet got a public key in the block chain (i.e. no transfers out, no aliases, no forging) != darkNXT

That 250million figure is including the latter, right? No way to distinguish between the two from a technical point of view.