i don't like the sounds of how it's being structured. seems eerily similar to the London Gold Fix and also how the banks have rigged Libor. anytime you get a dozen or so banks on the telephone to determine the price of something, you're asking for trouble. we know they rigged interest rates and probably have tried to rig gold as well.
from what Barry Silbert talked about on Bloomberg, doing a twice daily Bitcoin price fix based on what a bunch of banks say the price is would be ridiculous. i'd rather rely on Bitstamp to be quite honest.
We might have Bitstamp accounts and price ticker feeds in front of us, but many don't. And although there's obviously room for collusion on a fixing committee, it wouldn't last long if it was regularily miles off exchange prices.
An AM/PM (more likely midday/midnight?) fix would likely be useful, especially for the various ETF (or ETF-like) products being put together. For example, if you (as a punter) want to sell some of your ETF it obviously wouldn't be possible at last price, it would have to be at next price, so a reliable and generally trusted fix would be needed.