I've flown the Bus, 737 and 777. They all require some monitoring and ALL require help (via the speedbrake) to keep you on the path.

The biggest problem with the Bus is that if you have a speed restriction, the bus only gives you five knots extra to stay on the path. If you have a 280KT restriction it could increase to 285kts and then it just stays at 285 while you drift off the path. The FMA keeps saying DES while the Boeing will go to about 20 kts fast and then give up, but at least your FMA changes from VNAV PTH to VNAV SPEED.

The biggest benefit of the BUS is that after the first idle descent, the path is drawn as a straight line between the fixes as opposed to ALL idle descents on the Boeings. During an RNAV arrival you can change your speed via managed/selected speed and the path doesn't change. The Boeing would draw a new path based on your programmed speed. Doing a 300kt descent and being told to slow to 250 = no problem in the BUS and in the Boeing it means asking the controller if they want the speed or the crossing restriction.

Its sometimes comical to watch someone try to get the airplane back on the path by changing to FLCH/LVL CHNG and not increasing the speed and expect it to somehow get back on the path without any drag. It's far easier to just drag the speedbrake and leave it in VNAV/DES. Just my opinion.