Wearing mail for FR vs. Ragnaros

[Grul]

Was looking at the best fire resist items available for Ragnaros, and it seems that certain mail items have far more fire resist than any plate equivalent.

Comparing items in the belt slot:
(plate) Belt of Might thottbot.com/?i=26806
421 armour, 15 sta, 7 fire resist

(mail) Fiery Chain Girdle thottbot.com/?i=27636
214 armour, 10 sta, 24 fire resist

I've ignored the things that won't make a difference on Ragnaros (other stats, defense, dodge). The mail belt looks a lot nicer, as +17 fire resist over the might belt is a significant boost.

This is at the cost of 200 armour (<0.8% damage reduction), and 5 stamina. Ragnaros only does a small amount of physical damage to the MT in comparison to the fire damage he does too.

Comparing shoulder slots:
(plate) Dark Iron Shoulders thottbot.com/?i=8450
514 armour, 10 stamina, 10 fire resist

(mail) Fiery Chain Shoulders thottbot.com/?i=8450
299 armour, 10 stamina, 25 fire resist

Again, this is a huge boost of +15 fire resist over the plate item, at a cost of 200 armour.

Overall this would be a gain of +32 fire resist at the cost of 400 armour or so... Looks pretty tempting.

Any thoughts/comments?