Unfortunately I could't see the link you gave...I believe you have to register for this. :)
anyway, the site is not important. The important thing is to be sure this is what you want. If it is, then go ahead....Have fun. Everyone is allowed to do whatever he/she wants as long as they don't interfere on other people's life. And you don't.
But I have a question....Why do you care about what people think? You must realize there will always be people considering this "slutty" as well as people considering it "perfectly normal".
Nevertheless, don't forget the condom. And also be careful when you choose your partner, you don't want him to be aggressive or something and turn this into an unpleasant experience. Otherwise, have fun.