Textilet, what pros and cons have you so far come up with?
The sola 4000s is in the lower end of power but could probably work. But if I make an upgrade I want it to be a BIG upgrade when it comes to output power!
The brightest portable light of any kind I've seen in person was the Gates VL-24 at 6000 lumen, and that was..ludicrous. I think based on what one 6000 lumen light looked like, dual sola 4000's would be quite a lot of light. I would be more inclined toward the Keldan Luna 4 V for the price simply because of the color temp. I've noticed that having the warmer end of the spectrum represented underwater looks good to me, so I'm less inclined toward the solas with their somewhat cooler color temp (6500k). My preference for warmer color led me to look at the Keldan Luna 8 LA-V CRI (different from the Luna 8 LA-V FLUX); Steve Douglas wrote an great review of them which is online. I also found a single decent sample video of the lights in use underwater and I think the colors the lights produced are beautifully balanced and produce a unique look. At 4500 lumen they have lots of power.
The Keldans also have 5 power levels. The Gates only have full or half power. Half power with a pair of VL-24s would still be 6000 lumen, which would have to make blown out close ups a concern.
Keldans at low power burn for 200 minutes. The Gates only burn for 120 minutes at half power. Extra batteries for the Gates are about $1000.
The Gates are neutrally buoyant, which is great. The Keldans are a quarter pound negative each. Both Gates and Keldan cost about the same.
The Keldan Luna 8 LA-V FLUX has 6000 lumen at 5000k, but doesn't have the same color rendering index as the Luna 8 LA-V CRI. I don't really think I need 6000 lumen per light, and as I said before I'm intrigued by the color quality of the Luna 8 LA-V CRI, so thats the way I'm going to go. When I get the lights I will post sample footage (which is quite scarce online) and as complete a review as I am capable of producing.