Not so. The ship size was known to be comparable prior to the down-select. For the size of TAG, whether its Dave C or Dave wrong doesn't really change the price significantly, although going for an EM catapult solution adds risk (so don't do that then.....use steam).
In fact due to the increased performace capability of Dave C, you can actually get away with a significantly smaller TAG.
Oh and you get a much simpler MASC choice as well........
Oh and interoperability with USN and MN.......
Oh and a fallback if Dave C goes tits.......
None of which is of much import to our light blue friends, but has a great deal of importance in the maritime domain.