I play jigs and reels on an english concertina and it turns out very well. I spend a lot of time in ireland and I find english systems turn up more often than one would expect. I've heard captain Birdseye play and have his books and very good they are.

The anglo was much more available due to the large numbers made and distributed by Lachenal and clones like that and they were available more cheaply thats a fact. English models tended to be higher quality and therefore expensive in the main and its no surprise that in rural areas the anglo was played much more because it was cheap and available. Thats why it is the traditional instrument for morris in england, not because eof any inherent advantage or disadvantage in the systems, simply due to availability and price.. Stuart Eydmans work on the concertina in Scotland is interesting as the english system was certainly the system of choice for working class people which is interesting. I think thats down to the keys.

Each of the systems can play great music in the hands of experts and each of the syetems can sound terrible. Its a about the player I think.