That's exactly my thinking about the RNZN. The transport capability of the Absalons would enable them to fulfil the transport role of the MRV, but with more flexibility, & they are very capable (more so than the planned ships) of performing the OPV role, while the capacity to be up-armed very rapidly would mean that in necessity, the RNZN could very quickly add two new major warships, without having most of the burden of maintaining (stored weapons need little maintenance) & manning the weaponry in the meantime. Indeed, it could dispense with buying most of it in the short to medium-term, since it would be available off the shelf very quickly. The peacetime costs would be 1) probably a higher initial cost than the current plan (but not too much higher, IMO), & 2) probably a higher operating cost for 2 Absalons vs one MRV & one OPV. For the increased flexibility & capacity, I think the modest extra outlay would be well worthwhile.
I like the Absalons concept for NZ, but my one problem is that they lack the vital medium Amphib capabilty requried for operations in the South Pacific. If they can be fitted with a LCM and carry the Combat Boats then I've got no problem.