My opinion is that until we see independent measurements, and if you really want Neumann to either :
- Go with the KH 350 if you have room for them. It's a relatively big speaker volume wise, with a BR construction, the bass output will be much superior to that of the KH 310 II, and for where it's priced compared to the 310 II, it's absolutely worth it.
- Go with the outgoing KH 310 A. The mids and treble sections are basically unchanged, and the despite what Neumann said, my guess is that the increase output was for the midbass and above where the KH 310 A wasn't severely limited to begin with. Subbass limitations remain fairly high. For the price difference you might just want to buy a sub or two and enjoy the additional SPL and extension.
- Go with KH120II/150 with sub. Cheaper, arguably better horizontal dispersion than either KH310.