If he has listened to them and liked them, particularly in comparison to other products in their price bracket, why would the opinions of random strangers on the internet matter? It's him who has to be happy with the product.
I have seen them in stores, and admired their battleship-like build quality, I have been avoiding trying to listen to too many products because it reduces temptation, so unfortunately I didn't listen to them.
Edit: tried to add links to Japanese reviews in case you wanted to try feeding them to Google translate, and a YouTube video, but that seems to have triggered the spam filter