Been speaking to service guys at my garage. They have confirmed that the new gs will come with a non-servoed, non-ABS option.
They also told me that they'd had no servo failures on 12GS's to date either. They have however had failures on the older ABS systems, but not the 'Sports Integral' fitted to the 12. People come in with reported brake failures, but these have been due to the 'self test' at startup not completing. The most common cause of non-completion of the self test is a bent hand guard, which just applies the brake lever a fraction, so beware.
One thing I did also find out is that you will have a 'Brake Failure' indicated for the rear bulb being out, although when you check the rear light it will appear to be OK. This is because the ECU detects the failure and sends an increased voltage to the tail light to simulate a brake light......quite clever I thought.