Cherokee wrote on 02/29/16 at 3:18am:
The second bike was superior in many ways...better fork, shock, shifters derailleurs, seatpost, saddle, brakes, and I could go on. But none of those components had any impact when simply coasting.
The OP asked if better hubs would have an impact. Most responses seemed to deal with what hubs they liked and why. I thought I'd answer the question from my experience. Your results may vary.
In the real world, trail conditions, rider technique, tire design, tire pressure, brake drag, suspension damping characteristics, and to some extent suspension geometry all have an effect on conservation of forward momentum while coasting. As does wheel bearing friction, and freehub friction.
When you change all of those things at once, the net result can be a perceptible change (for better or worse).
Other things to consider... riding an all together better bike can allow for more rider confidence, which can result in being able to carry more entry speed into the flat sections where you would coast through. The bike taking off after cresting a hill (i.e accelerating) likely has more to do with a lower moment of inertia on the better (lighter) wheel/tire combo, and to a lesser extent, lower overall bike weight. Less mass to accelerate results in quicker acceleration.