Question about Tier 2 runes vs Tier 3

I'm curious at how much of a detriment it would be to take Tier 2 Armor Quints vs Tier 3 Armor Quints. It's about 3 armor that I lose.

I've been supporting Nautilus. The most successful rune setup uses Armor Reds, Armor Yellow, Flat MR Blue, and Armor Quints. I have all of that except the Armor Quints (just HP quints atm). How bad would it be to buy Tier 2 Quints instead? With the rework of runes coming up, not sure how much I want to spend on Runes right now... just in case they go away without compensation.