Joe,
Now, I know this is not a true test, but I put the fly in a bowl of water 2.5 hrs ago. The hair has flared more, but it is still floating high. When I put traditional dry flies in the "bowl test", I usually get a sinking in a half hour or even less.
Granted, in moving water with the natural wetness a fly would receive, it might not repel water as long, but I think it will do well floating...........
Update: Still floating well after 9 hours.