Posting in here should only be a potential problem if you
1. Advertise
2. Set up a date on the board
In either case I can see LE making an argument that you were communicating for the purpose of prostitution in a public place . . . Describing past events may aid LE in that they know which providers to key on, but again, prostitution is not illegal.
I don't know whether assisting someone find a provider could run up against the "procuring" rules. I don't believe any LE have ever tried anything against posters on a site. Even if they get your "identity" from your internet service provider, who's to say the posts in question were not made by your co-worker, best friend or crazy uncle??
Apparently. to stay within the law, you just make sure to book the date over the phone and meet initially in private, like a residence or hotel room. This may not prevent the police from trying to harrass you as a witness if they are trying to bust a provider or agency though.