I don't know man. ATI is a sweet light. If you want it, get it. You can't go wrong.....but for most reefers the other two options are more easily met. Upfront costs normally drive the purchase.

Your calculations are nicely done...however I personally only spend $80 per year on new bulbs 2 x 250w MH. You are calculating top of the line bulbs that aren't exactly the average cost. my point is....you are talking yourself into the ATI fixture....so just get it man. Also....I don't know anyone that has kept the same light setup over a reef for 5 years anyways. I think 2 years is common.

You might as well just calculate for 10 years and then you will easilly purchase the ATI fixture. : ) I'd get it if I could.