If you ever consider playing Irish trad tunes, the anglo-system ("D" for the standard session) is definitely a must!! You will never achieve the same rhythmic precision with an English concertina. I must admit that regarding song accompagniment there are drawbacks in the flexibility of keys. But for dance music the anglo system is superior. (I am an Uilleann piper myself, but my wife plays concertina, and we have a couple of concertina playing friends in Ireland.) Josie