I did not mention anything about the cost of rockets persay or specifically mention SDI so dont attempt to re-evaluate what I have written to make up for the flawed logic in your principle argument.You talk about rocket launchers as some sort of SDI initiative hugely expensive and ground breaking, it is fairly standard proven stuff. I am well aware of the need for a heavy maritime emphasis on defence, I just feel for a country that is only prepared to allocate a modest amount to defence (I make no call on whether this is right or wrong). Traditional ASW focused Frigates do not represent good value. A well armed OPV even something like a KD Lekiu (maybe, just 16 ESSM instead of Sea Wolf, torpedo tubes and the 57mm gun and a helicopter, slightly slower with a longer range) would be much better value for money. The RNZN could then afford to operate say 6 rather then the current 2 + 2.
My point about HIMARS and M777 were examples of things that should have greater priority than a 3rd frigate, earlier I did point out other such needy cases: the Orion and Hercules which like the artillery are very old and should be priorities for replacement.
Yes the sort of maritime work RNZN needs requires greater numbers, but not hi-end frigates to deal with submarines.
A heavily armed OPV? A Corvette? Again take out the world map and see the distances that need to be covered. A general purpose frigate / long range surface combatant (120m+) call it what you will is the minmum required vessel. OPV's are fine for NZ EEZ work but not for a maritime nation stuck in the middle of the largest Ocean in the world with the longest SLOC of any country.
Also I did not say anything about a high end frigate - a general purpose frigate along the lines of the future C2 rather than C1 or planned AnzacII is most appropriate as it has the required automonous mission range, task flexibility capacity to deal with the various conigencies that a kiwi frigate might find itself just like the previous Leanders and current Anzacs have done over the last few decades.