design wise the un-staggered is actually better by design. technology has improved, and its recommended that if you can, not to break the wax on the models that have hex or flat-head adjustment options for hum-canceling reasons. hence those that prefer to stagger them, they offer it as an option from the factory as to not break the wax.
the staggered pole pieces will have different magnetic characteristics in reference to how the coils are wound and also very very slightly with volume on a string-by-string reference. but its alot more minute' than you think volume wise, almost negledgable. the pickup height in reference to the strings will have more of an impact for volume/tone adjustments.