Kerb the guests I say
except me of course - honest broker I be.
I have to say it will not deter tose few determined trolls but the average folkie I find (and I was no exception - even as a PC literate) posts first and joins second.
We will not get the second post if the first is too difficult.
trolls will know how to delete their cookies but then naive users are unlikely to so they can be monitored. Tough one Max, big brother and all that. With you whatever you decide.