Stomach sleepers tend to wash a bit (with your toes pointed the footbox gets longer)
Side sleepers can get away with a bit shorter quilt vs stomach and back sleepers.
But yer specific quilt- for a colder weather quilt go with a long. (I'm 5'10")
My standard quilt is a bit longer than EE because it's nice to have a few inches of quilt to roll over as a draft collar in general.
Their long is 7' if I remember right- and in colder weather especially- if you get a bad night the extra length can be used to form a hood that will let you push the temp rating a good 5* or more if you curl up a bit at little to no weight penalty. It's an ounce or so of prevention lighter than any other option- it also gives you a bit more down to shake down in a real emergency if you need to "overstuff" the quilt and ball up into a shortened quilt.
Not to confuse things too much- but if going wide long in EE- it might be worth a quick look at the convert series. When going below freezing there is still a lot to be said for being able to zip up completely and the extra ounce or two may buy you a lot of versatility for a relatively expensive piece of gear.