The B version sounds more elaborate.
It's not elaborate but is complicated. The throttle going in ARM and HOLD mode at different stages is not very intuitive according to NTSB after SFO and during certification of 787(which is similar) both FAA and EASA were not very comfortable with the design. It's all mentioned in NTSB report. Airbus OP DES or DES modes are straight forward with no fiddling required from the pilot.