My E55 had no problems either but I sold it way back in 2013. There was no brake feel at all but the 8-piston Brembos would stop the car faster than crashing into a brick wall.
From what I’ve heard it’s a very reliable system just comically expensive to fix anything other than the accumulator ball and a warranty takes care of that problem. I think after a few hundred thousand pedal cycles it’ll pop up a red warning to inspect the system or something like that.
One thing I did have was gas smell issues but the dealer decided to throw me a bone and fix it, this was before the recall campaign.