I ended up with one by mistake in April. I had a Cam mounted on my board aiming out, from the nose... I fell off and broke the mount off the board with my knee. The waves where good, and I didn't want to go in... so I stuffed the "floaty backdoor" in my mouth.
It actually works great, easy to breath... very secure, no problem during a wipeout... I tied the tether to my wetsuit zipper pull as a backup to the floaty.
It takes great movies from that vantage.
Really isn't a bother at all. I still use it that way from time to time... less trouble than the headmount... great angle and aiming towards other surfers.
You can see the deck mount is still intact... it actually took the paint right off the board