Generally, I've found that bigger tanks pencil out worse with LEDs, especially 'puck' style LEDs like Primes. To light a 6x2x2 180 with AI Primes, for example, would take enough of them to be silly. A 5 foot 6-8 bulb T5 would light a 180 very well.
To compare a 5-6' tank needing a 5 foot T5 fixture with 6 bulbs (longest Blade is 57" and longest T5 is about the same) with 3 of these Blades:
6 bulb Sunpower:
New Fixture - 672$
6 New 80 watt bulbs - 150$. 4 sets = 600$
480 Watts
Total with 4 sets of bulbs over 5 years, assuming changing bulbs every 15 months = 1272$ over 5 years
3 57" Blades:
Grow x 2 + Glow x 1 = 1670$
360 Watts
Total obviously = 1670$
Electric and electric rates complicate things. For me, I run my lights for 9 hours a day at about 11 cents per KW*Hr. So for me to light a 125 or 180, assuming saving 120 watts with the Blades over the T5s:
(120 Watts / 1000 Watts per KW) x 9 hours x $0.11 = 11.88 cents per day = 43.36$ per year = 217$ over 5 years.
Final total including new fixtures and new bulbs for T5s including electrical savings of LEDs:
T5 = $1489
3 Blades = $1670
That's actually closer than it usually is when comparing T5s to Name Brand LED fixtures on medium/large tanks. So, financially that may make sense for some reefers. It certainly makes more sense than buying 12 Primes or 6 Radions or whatever it takes to light a 125/180.