When I bought my E92 335d I did so knowing that the ABS/DSC unit was throwing up faults. I whipped it out last Monday and took it up to 'ECU Testing' who returned the unit today (well, yesterday now!) fully fixed and with a lifetime guarantee for an all in price of around £240.
Fitted the unit, bled the brakes, perfect.
For anyone else trying to do the job, it's a bit of a bugger getting the unit in and out as there isn't much room. It helped to remove the bonnet stay and use a broom as a bonnet prop, there is enough movement in the brake lines to persuade them out of the way and you will need a magnetic 10mm socket to remove the three mounting nuts 'cos there isn't much room, they are a long way down and you are likely to lose them without one. I didn't have one so I carefully undid the nuts 90% of the way then used a magnetic pick up tool to undo them the rest of the way and remove the nuts.
I followed the advice of using a pedal pusher on the brake pedal and relieving the pressure from the system via the caliper bleed nipples before removing any of the brake pipes on the unit as this vastly reduces fluid loss and capped all the pipe ends while the unit was away. For once I didn't make a godawful mess everywhere!
Very happy bunny with the service and the price. Highly recommended.