I won't argue over which tree is better--I have different preferences depending on my build--it just seems odd to me, since shields are for soaking damage and opening up for counter attacks (the latter of which I suppose would help a light build), and it so very well compliments heavy armor's focus on tanking and stagger absorption. Also, 10% reflect > 10% dodge: that's a 10% chance to reflect all damage from a single strike, and, as I understand it, not take damage from that strike--essentially a dodge/counterattack. If I'm wrong, however, and the PC retains all the damage of a reflect while also reflecting it, then perhaps YMMV; whether dodging an attack outright is worth more than taking the hit and giving it back depends on the player.
Anyway, I find this very interesting. Such a build sounds nice at higher levels, but what about getting there? You're still soaking up damage with an armor type that's not built for durability (and I realize all armors can reach the cap, but I was/am not considering that).
I think you're overestimating heavy, it's not that much better than light protection wise.
Early on, most of your armor rating is going to come from simply wearing any armor, since you get 100 just for wearing helm+armor+gauntlets+boots, another+25 for shield. For some reason shields give armor though it doesn't make sense to me, anyone's guess why they think it should. Armor is also, in the end % based, another odd design decision. But for some reason they display meaningless numbers instead of your actual mitigation. Anyway, mid game, heavy will start to make a bit more difference protection wise, but is also a drain on stamina until quite late. By the time you can get rid of heavy's penalties, which requires 70 skill and three perks two of which are useless for most players. Light armor isn't significantly worse protection enough to make heavy attractive.
Let's just take an early-ish character for comparison-
Full Elven w/Shield, 25 armor skill, 1 perk for 20% increase = 102+125(base) = 27% physical damage reduction
Full Dwarven w/Shield with equivalent = 134+125(base) = 31% physical damage reduction
4% more mitigation, really worth the extra weight and higher sprinting cost?
The gap will widen more mid-game, sure, but then it'll close again. The real deciding factor is which has better perks/costs fewer perks. The answer is light armor in both cases, due to conditioning's svcky placement in the heavy armor tree.
Reflect also doesn't work like the effect in Oblivion, you still take the damage that gets reflected.