Which is more dangerous...Hmmmm! If you are are caught surfing porn on your work station or you miss a meeting or two or can't get sleep at night due to surfing porn and you lose your six-figure income prematurely, then I would say porn is worse than prostitutes. If you catch something and pass it on to your significant other or if you are caught by a police decoy and your name and face is made public on the 6 O'clock news and you lose your six-figure job then I would say the hobby is worse than porn.
All things in moderation. Moderation is the key.