really, not allowed to go to another company for 12 months. I don't think we have anything like that here in the states. hmmm well, we do, come to think of it. The thing is, I try not to burn any bridges if I don't have to. However, if it comes down to a stable job that has growth and it's what I really want to do, I'd go with that. It is a tough call, I guess you'd have to look at the long term benefits of the jobs and go with that.
I would contact an attorney. That is a big commitment to make if they still have the right to fire you or lay you off without severance payments. You could land in a position where you have no job in your field and are not allow to seek one. I have been there, done that, and bought the t-shirt and it isn't a nice experience. If they don't want you to go to the competition for 12 months they should be willing to continue to pay you for that long if they let you go for any reason. Just my advice on contracts like that. I am not an attorney. Anybody who takes my legal advice without consulting an attorney should consult an attorney.
I agree with Chefy, you need professional advice, be safe, be sound... I'm not famous yet to support you! ;-)