JagRigger: Given that the only yard which can (realistically) build 'em is Barrow, the answer is a very straightforward no.
Personally, and for the added flexibility / redundancy it would confer, I'd like to see some sort of 'mini triad' option - this, however, is clearly not on the table - for many reasons, not least of which cost. Given that this is a non - starter, any argument for systems other than SLBM is wholly specious.
Regards,
Frank