This is an interesting post, and I am currently in the same boat and looking at an upgrade, albeit to a slightly different instrument. I'm playing balkan and classical, and currently have a Hohner organola, 120 bass with double octave, but tired with messy key mechanics. Its a great instrument but now that I'm sure I want to invest a lot of time into the accordion I would like something nicer.
I've narrowed my search down to a few makers, and for me keyboard mechanics and the feel of the instrument is very important. I would like something with cassotto, and if possible a free bass converter. But wouldn't we all! I'm on a budget so I'm not sure where to go. I'm planning on heading up to Accordion Lounge in Shropshire UK to try a few Bugari and Giustozzi models which should be fun. I'm also considering heading over to Prague to take a look at the new offerings from Delicia (and have a few beers of course, but I'm going for musical research, honest)
I'm not sure if free-bass should just wait, and I should get a mid level Bugari (I think it would be used at my price range) so I can really focus on the right hand and keep playing at an intermediate level with a good quality instrument. Any input from experienced players would be appreciated, although I'm developing an understanding of what I want to play I haven't had an opportunity to play many instruments in this price range, and I've found some trouble finding dealers stocking what I'm looking for