If my character is Light Armor only, and has perked the light tree, with the ones that give bonuses for using all light armor... would using a heavy armor shield ruin that? Would I be able to level heavy armor off of the shield alone? Does it matter what type of armor the shield is classed as?

Was reading the UESP armor page earlier, apparently it doesn't matter what kind of shield you use, you'll still get the perk bonus.

Awesomeness. Thank you very much good sir/madam.