Sorry I could not contribute this comment as Ive been away, but yes, get the Long bag, for many reasons. Of course your height, but you will also have more room for layers, and could fit a second occupant in an emergency, can layer two bags one inside another, etc.. Things you can only do with a super-stretch.
If money really is the object, get a new 2006 from the outlet in Japan, about $75 less.(I could help you with that) In fact I'm buying a new #5 long for a BPL member tonight. Only problem is choices are limited. I might have to get him a 3 or 7, or zippered (he wants zipperless).