As an ASuW missile the Penguin is an advance on the Mavericks we had. AFAIK our Mavericks were the A or B mark and had the Optical Electro guidance which relied upon contrast to detect the target. If the visual contrast is poor then the missile has difficulty locking onto the target. We now have the Mod 2 variant of the Penguin which is IR guided so it depends upon heat contrast rather than visual contrast. It also has a longer range. The Penguin also has a 120kg warhead compared to the Mavericks 57kg. The only advantage that the Maverick has over the Penguin is that it can be used against shore based targets.Good post. I've made that point about the Penguin before too. It seems NZs offensive weapons capabilities as outlined above (Penguin, Mk82) are so tactically limited as to be useless, which begs the question, why bother acquiring them (Penguin) or retaining them (82's). I guess with the 82 it keeps the armourers skills up. AFAIK, we have sold the Mavericks to Peru, as they no longer fit with our new Seasprites.
Replacing the Mavericks with the Penguins seemed like a simple replacing X with Y transaction. Basically because that was what the new sprites were wired for. On paper we have acquired a bigger stick with more range and bang, but not really gained any new capability, and if anything, lost a tactical CAS capability.
Wikipedia gives $22000 (?USD) for JDAM tailkits. This is probably no longer accurate, but my guess is that they are still way cheaper than any other PGM.
Regarding X v Y replacement generally X will always be a generation ahead of Y because it's technology is far more modern. Hence X theoretically offers greater capabilities - more bang for buck so to speak. Don't forget with the new Sprites we got a steal and since our mates across the ditch had already paid for the integration of the Penguin, well we'd be fools not to take them.