Not so Andy, I thought I had commented to that effect on a previous thread? Such is the overlap in wing formulae/biometrics between the two that there are instances (uncommon) where a bird cannot be identified without a feather sample. LS gives the following values for emarganated p6; Sykes's Warbler c45% strong, c50% weak and c5% absent and for Booted values are c25% strong, c55% weak and c20% absent. So, it is not diagnostic, but one of multi characters that needs to b taken into account.
Grahame