The only difference I have found between the US and UK sold cameras is the price, much cheaper in the US plus Sony will not allow any US sellers to sell it outside of the US, (protecting it's UK/EU markup).
Yes, although the US page has the included case listed under the Features tab but not so the UK page, the case is listed as included in the UK Specifications tab, so I was wrong.
Looking at some of the early customer reviews on the US site for both the wifi and non-wifi versions, and having downloaded the manual, one annoying drawback seems to be that the fixed mount options all involve using the waterproof case, which seals the camera in, of course, and muffles the audio. However, one review claims the case muffles the audio, another says it makes little difference, so perhaps more reports needed before jumping to conclusions.
The helmet strap BLT-HB1 seems to use a different clamp arrangement that doesn't need the case (another headband mount VCT-GM1 does use the waterproof case, btw). It may be that a bar mount with decent audio would require some surgery on the helmet mount to clamp it to a bar fixing but I'll wait for some more user reviews to see what happens.
John
