Its the Deep Blue Sea lights that are no longer made that can retrofitted with with HID, Xenon or LED depending on your preference. Most Cabos had the Deep Sea Blue 150w HID lights.
Yeah, I manage a 2007 boat that had them installed back then in 24 volt. They were like flashlights. The new owner traded them out for the newer version which is a lot brighter, but not as bright as some of the others. I think they charged him something like $1800 a fixture for the newer version. They're still working without any issues. The fixtures are plastic but don't seem to have any problems with cracking
I used Seablaze X. I have 4 across an 18' beam and I could definitely use 2 more. They are great lights so far.
After spending over 3K for Ocean LEDs they failed exactly one week after the warranty expired. Told to pound sand. Never buy Ocean products
SeaDuck http://aqualights.us/ said they repair a lot of Ocean Underwater lights if your looking for someone.
I installed 3 Aqualuma 3-series in 2007. Work well, no failures. Can be removed from inside the boat if there is a problem, but never have. Back then they had 'wide' and 'narrow' beam widths. 'Wide' were recommended, but in hindsight, I should have gone for narrow - they would throw the light further.
If you are having issues with fouling/growth,try putting a light coat of the clear coat from prop speed. Works great.
Fouling has been a slight issue, as with anything else that lives in the water all the time. My boat has twin sterndrives with stainless steel props. Basically my regular maintenance consists of wiping the props and underwater lights with the plastic scouring pads about every 2 weeks. I can reach both by lying on the swim platform.
Current Report - Cabo 40 - My neighbor just replaced his Deep Blue underwater lights with the Aqualights.us LED. He was able to remove the inside of the Deep Blue and replace the guts with the Aqualights.us without having to haul the boat. They fit perfectly. Also, he removed the 110v breaker wiring on the back side of the electrical panel and moved the wires over to a 24v breaker without having to run any new wires.
I think you also need to consider the location. For example in San Diego Bay with murky water we have 4 of the Lumitec SeaBlazes3 on a 14 ft beam and not very impressive.