The battery case on my 250s is broken so I am trying to decide whether to replace the 250s or spring for the 300s. I understand the 300s come with a hard case that fits either headphone, but I can get that a la carte for less than $10. Can those who have tried both the 300s and the 250s verify whether there is a difference in performance for the air traveler as far as noise canceling, comfort, and/or acoustics? The 300s run $150 on Amazon, while the 250s are only $60, so there's a pretty big gulf in price.