I can't figure out why they are charging almost twice as much, with only minor tweaks to two of the drivers.
Additionally, the new speaker needs to address the real Achilles heel of the previous design, which was the very considerable resonances of the (metal!!!) 'cabinet' (frame). I found that covering many of the exposed metal flat surfaces with adhesively backed neoprene killed most of the very noticeable frame resonance. For about $175 you can get enough 1/8 inch neoprene from VibraSystems to do the job. No one seems to have ID'ed this issue, but my listening tests suggested that this treatment of the metal surfaces does clean up the speaker a bit. Of course a direct A/B comparison would be best. I suspect that if John Atkinson at Stereophile ever reviewed this speaker (either the 3.1 or the new 3.5), he would climb all over the resonance issue. Tribute to the rest of the design that they sound as good as they do.
best, DW