I don’t think the KK 62 using the same caliber as the rifles actually matters. Its ammo is belted and the rifles’ isn’t, so in the field it functionally can’t take rifle ammo. (Also like it or not, Finland is gonna switch to a 5.56mm AR because everything evolves into crab.)

Full power vs intermediate cartridge has all the normal pros and cons, but the PKM itself is very light for a full power MG. It is a proven machinegun that is about as light and handy as something of its caliber can be short of whatever engineering tips Eugene Stoner’s cocaine fueled ghost whispered in the ears of people designing the LAMG.

I almost wonder if 54r ammo will become an endangered species at the winddown of the Ukraine Situation, but other than that PKMs are solid choices.