Hi Wayne, my tank is 72x30x30. Looking at a single unit for that tank, I see two comparable options:
http://www.jlaquatics.com/product/vt...2+Inch%29.html (almost $5k
)
http://www.thereefshoppe.ca/index.ph...4b84f6d9596c71 ($4k)
If I look at the Key model you mention, the largest unit I see is 78cm x 27cm at $630ish. I'm not sure what kind of coverage you get off that, in the worst case scenario though I could fit 4 of those over top of my tank and $600*4 = $2400, still a pretty respectable purchase price.
I was looking at these Orphek units that fit inside a T5/T8 socket and they look pretty neat but even then it looks like something like $160 per unit (I assume they mean one T5 replacement). I assume that it's fair to expect 5 to 10 times the longevity out of one of these over one T5 lamp so maybe that's fair but then you lose the ability to "mortgage" that part of the tank expenses over time.
I have very little doubt that with most units available today, that most people don't "regret" the jump to LED, per se. I doubt I'd regret buying a Porsche one day, although that doesn't mean I can afford to get into one. Life's funny that way.