.. doesn't it come down to using ALL the various bits of information to come up with a big picture ? .. and then play with the beast as necessary to achieve the aim ?
Basic scan is critical and at risk as the cockpit presentation simplifies ... hence the need for intensive I/F work in the endorsement phase .. as, in many cases, this is the only time where there can be made time to do it ... ?
There may be a variety of personal preference and emphasis ... however, if the basics are well grounded, then the result is going to be similar.
As for me, if I didn't fly the ball principally, then just the airspeed didn't work anywhere near as well ..
Apart from the sometimes quite different panel presentation .. does there need to be a fundamental difference in scan pattern ? .. restricting my comments to the aircraft with which I have a familiarity, it always appeared that the pilot who looked through the F/D, eg, to the ball information beyond, flew far smoother than the automatics slave.
As is often said ... each of the gadgets gives a bit of the puzzle's answer, albeit that we might emphasis this or that gadget's information a little at different phases of flight ...