Beauty is in the ears of the beholder. Personally I think the 300 is a beautifully balanced and poised amp, an iron fist in a velvet glove type deal. At it’s price point it is peerless.
The 250 is another kettle of fish altogether. It’s got something approaching a cult following. I don’t like it at all. There are better sounding power amps for less money.
I’ve never heard a 272. The anecdotal feedback is that it performs well above its price point and is exceptionally good value for money. The LP12 would probably benefit from a 252 and the system in its current configuration is well positioned for the insertion of a top pre amp, should your friend wish to upgrade in this direction. A 552 would also slot in there very nicely and work a treat with the 300.
Of course, if your friend is into streaming, pay to play, and all that stuff, the 272 is the best Naim pre/streamer he can currently have. Going for a separate streamer would add more boxes. Does he want more boxes? Can the accommodate more boxes?
The last thing to take into consideration is how it sounds. What your friend has is less important than how it sounds. If it all clicks together and they like how it communicates with them, that’s all that matters.