The NZ OPV, at 1900t look nice. The trouble is that knowing our Navy they will add this and that. Replacing a 270t boat with a 1900t ship, is going to be expensive.
A few 1900t OPVs maybe (3 or 4) could be ok, but to replace the amidale class, and then to replace the Cape class when they start to crack up again, what are you going to use. Bigger ships are nice, but a ship can only be in one place at one time. For the same money smaller boats allow you to be in more than one place at the same time, as you can get more of them
The Ecuador boats (minus all those missiles) are not as good as larger boats, but I bet my bottom dollar they will be cheaper to run, this class is going now for 30 years and still going strong. These boats can go at 36knots, not bad. Yes the small size means that they could only operate a heli occasionally, but that is better than nothing. It may need to be strenghtened (the heli deck) so that a SH60 can land and drop off a few things, before flying away, but there seems a lot of deckspace there, plus getting rid of the SAM gives some more clearance, plus remove the aft gun, and it could go aft a few more feet.
I know this is getting into opinion... I think this,, someone else thinks that..
It looks as though we are going to get 1900t OPVs which are going to be very expensive (I have zero doubt about this), and the lower teir will be the customs boats (customs patrol boats replace Navy patrol boats), which will last 10 or so years, and then need replacing. I am just saying that the lower teir could (should) be 600t boats, with more space, better seakeeping, better comfort, longer hull life, a heli pad that could be used occasionally (dropping off special forces, dropping off supplies, parts, picking up sick or injured crew) , the downside of a deck is a little more weight (no moving parts). Getting rid of all those torpedos, missiles, sonars, radars will save a huge amount of weight and cost.