Is "pro wres" really a romanization of that katakana?
Anyway, Japanese people use different romaji all the time, so I won't quibble. If they can say Erikku Kuraputon and Makudonarudo, then Westerners can write and pronounce プロレス as "pro wres."
I think in certain contexts saying puroresu is OK. Like, "I went to a puroresu show in Japan." It is, after all, puroresu[/] in Japan. And since it's katakana, some Japanese aren't sure how to pronounce it, either, especially if they have no interest in wrestling. As far as I can tell, there's a long way and a short way to pronounce it and it depends on how familiar you are with the term. Japanese is a bitch to pronounce anyway... I do have to say that on the radio show they mispronounced practically every single wrestler's name, but I can't pronounce Tsuruta or Tenryu to save my life.
It's dead in Japan anyway. People on the internet care way more about it than Japanese people do. It's like a relic from the past over here. They're all about soccer in Japan.