Good work! I could easily switch between the 6'2" and 6'4" for average days, but I reckon I'd suffer on the smaller days on the smaller board. I think you'd be fine on either. Good luck!
Just FYI I am thinking of getting an Alt at 6'6" for hollow days in bigger (but not huge) surf...just reducing volume a touch to add more control. Having said that I've never felt out of control on the Alt.