On missile boats for Ukraine

Yesterday was the signing of a Memorandum of Implementation (MoI) between the UK and Ukraine to upgrade their Navy, more details here: Babcock to enhance Ukrainian naval capabilities. As part of this arrangement, the UK is going to build them 2 missile boats, with 6 more to be built locally. These will be based on the Vita/SuperVita class ships built for the Qatari and Greek navies.

(image source, and more info on these ships)

Given how these ships were built in the 90s it's interesting how this design is still useable (albeit we don't know much updating is needed), it makes me wonder about the need for new designs of destroyers and frigates, when historically most ships were incremental improvements on the proceeding class and clean sheet designs were comparatively rare. I wonder how an updated T23 would stack up cost and performance-wise compared to the Tw26 and T31, and whether the T45 could be used as the basis for the next-gen T83 destroyer.

I also wonder if a derivative of the Vita class would be useful for the RN/Border Force, the Damen 42m cutters will need replacing in a few years, and replacing the minesweepers with autonomous systems will leave few smaller ships for patrol duties. We probably won't need the missiles but a flexible mission space, maybe capable of carrying autonomous systems could be useful.

Update: as part of this deal we are also giving or selling the Ukrainian navy 2 Sandown class minehunters. I just checked wiki and there is one decommissioned but still awaiting disposal, HMS Walney, while HMS Ramsey is listed as Dormant on standby', so I'm guessing it will be these two.