Without wanting to sound too much like an expert of dodging debt companies, this is what I know:
Some companies with contracts like these will chase you up. Some will not. Adobe, for example, have never chased me after I've broken their 12 month deal. A couple of times, in fact. And I always end up going back, so it works well for both of us. Some, such as phone companies, will chase you for as little as a penny. I had a phone company (who I am actually back with as they've been quite good to me lately) chase me for 3p before they finally gave up.
Also, if you hold out long enough, many will offer discounts. I paid a fair few off through waiting until I could afford something, at which point I usually got a substantial discount (often 40%) to pay now and write it off completely. However, some will chase you to the ends of the earth to make sure that you pay up. WWE I imagine wouldn't be that kind.
The only real companies I've known to be dicks are gyms. If you miss a direct debit, they're on your ass within hours.