It is perfectly viable to wear heavier armour as an archer but as soon as you plonk on a helmet, good luck aiming. All helmets are too big for archers and therefore slip over the eyes... At least thats how I quantify my inaccuracy and extreme use of a straw hat!
Although I wouldn't wear any head armour and I do occasionally switch out to wearing heavier armour, such as the mail shirt (which is a mere 10 extra body armour and a loss of 4 leg armour against my Jerkin, not a very good armour/weight ratio.) due to the three times increase in head armour, I could in effect, wear the equivelent of 6 weight in head armour, so 2 weight...
That's a Nordic Huscarl's Helmet that provides 40 head armour. That's where things start to become a little unviable for really being accurate with archery given 6PD, MW Longbow & 160 wpf. Bascinet at 2.3, hitting on 6.9 weight is a further increase of .9 for 4 more armour!
As I say, I don't care and I think what we have now is fine, but I thought I would throw that out there.