Just a small pitch: I have been playing English system for the past 30 years. The big advantage is that when you have some guy leading a song decide he has to go to E flat or some other key beyond the basic 6 it is easier to play with them than it is with a diatonic. It's certainly cheaper than having to carry several instroments to be able to join in the fun. If you are going to stick to the British Isles music, certainly almost all of it is right for the diatonic. Once you go further afield, some sort of chromatic is called for. Besides, even harmonicas are getting expensive, nowadays.