Blocking only sorts part of the problem
From what I know about Phorm, a lot of the problems are caused by it reading where you're going and logging that data, so even without scanning web sites it's going to be able to figure a lot about you. Just URL alone will help for keywords (like Google does).
As for blocking the webwise system, what'd be useful is to know the IP ranges of the bots esp as their robots.txt knowledge seems to be essentially zilch, ie: not offering a user agent. Wonder what user agent they're going to use, eg: fake it?
As a sidenote -,interesting to see they're trying to sell this as an anti-phishing system as well as advertising tracking. Can't imagine how that'll work, and there are so many better systems out there that we don't need another faked one. Oh well - hopefully they'll get closed down by the EU.