It's just the diatonic accordion is the most complete! Its 18 bass total libertée allow accompaniment and more ... ! Personally I find that there is no better as a diatonic accordion, although it is quite heavy (about 6kg) is an accordion Castagnari (that's what I prefer, it's safe, the keys are very nice and do not move the reeds casiment level accuracy). The pitfalls of this instrument is its price: about € 5,000 if you buy in Rennes, € 3800 if you buy it in Italy. Qd as I said you get what you pay, the price is justified in my opinion.