^^ on my 2013 535xi the hydraulic steering is definitely different between Sport and comfort modes. I was surprised since i thought this was only limited to the non Xi models with the electric steering but i am 100% sure it is different between modes. In comfort mode the steering is feather light and Sport mode feels more heavier when you are about mid way into a turn. I noticed this because although its heavier it still feels artificial compared to how my E90 335 felt.
Current - 2013 N55 535xi Msport SAT
Retired - 2009 N54 335i Msport 6MT
Retired - 2000 M52TU 323i ASA Supercharged 5MT
More photos of my car here