Hiya sharpshooter.
"Pulling" speed may be the quickest way to get to a cleared FL but it is not neccesarily the most efficient. The 'bus (specially the 321) has a tendency to lag a little at the higher FL. Ie ROC = <400fpm, if one is particularly heavy. One course of action is to go selected speed and reduce speed by 5 kts or so, Causing a kind of mini zoom climb, this is quite useful if you only have maybe 2000ft to go.
My company sops explicitly forbid use of VS at all above a certain flight level as the Aircraft will disregard speed to get its desired ROC, possibly leading to alpha prot etc.....
With regards to your post, leaving the aircraft in managed speed for the entire duration of flight is more efficient, however it is very rare that one will be able to do this as ATC constraints, etc exist on nearly every route I have ever flown!
Tacho