I think the stock calipers hold up really well to track abuse. The mentioned upgrades (pads, titanium shield, as braided lines, DOT4 fluid) are all things you'd want to do even if you get the bigger calipers.
If I were in your position, I'd do the upgrades and pass on the upgraded calipers. Unless, you want them for cosmetic reasons, then with your discount, go for it!
If I were in your position, I'd do the upgrades and pass on the upgraded calipers. Unless, you want them for cosmetic reasons, then with your discount, go for it!