You could take the view that breaching it will be annoying, but as you don't contribute to AFPS you're getting less of something which wouldn't cost you anything anyway. You could take the view that the state regulation will change and that the LTA will increase again once the state has successfully pruned out the higher earners and saved itself money.
A lot is going to depend on your own circumstances; are you looking at a long second career which can allow flexibility with your remuneration package (the latest TUC report this week, shows just how many senior execs are now longer being remunerated via the pension wrapper), what are your views on your dependents getting a larger pension in the event you died etc.
The annoying this is, your salary is abated to reflect a notional contribution, so if you elected to leave the scheme, you don't get paid any more. If I were you, I'd get an annual statement so that you can make an informed decision, or at least put things in context.