Sharp practice is very Character driven (You don't activate units, you activate Personas that can activate units + unactivated units can shot during end turn segment)
Its great system and my favorite but its more meant for storytelling than for very competitive play.
XRampant rules are very streamlined and activates units (characters except commander have no place in this game) It si simpler too.
I will buy it for sure despite my dedication for Sharps practice.
I think it will work much better with the period than Songs of Drums and Shakos - that is cool little system but strikes me as not very Napoleonic* in character..
*if any 28mm skirmish could

IMHO SP fits it best.