I'm suspicious of manufacturer's light output claims unless supported by an ISO or CIE test method, and those appear to be thin on the ground.
You didn't mention your use, still, motion, studio, locaiton, high powered keys, lowered fill, etc. etc., so it's difficult to recommend.
We use Lightpanels 1x1's and the smaller sizes and just recently purchased an Ikan set.
The lightpanels are fairly robust (though the Dc convertor connection is somewhat loose).
The ONLY reason I use led's is the power draw and speed. The 1x1's are all rigged to hold V mounts and of course they all run 240 to 110 if your on mains.
This was shot with one small led hand lightpanel held and a reflector
I do like the Ikans, can't be sure of the reliability as they are new to us, but have traveled once and gone on location once without issue.
LED is a strange animal. It casts easily with digital, especially the variable daylight and they are somewhat specular. They produce more light than you would think but it's kind of a hard light, even with the soft versions. I would suggest cutting some spun sheets (1/2 stop at the most) to smooth them out.
They also make brackets where you can mount 4 1x1's into a larger fixture, though Ikan also makes some larger lights about the size of the medium kino flows, but once again they need some light spun to make work well.
This was also shot with lightpanel leds, for Key and accents and one broncolor HMI very lightly bounced for fill, with the leds turned warmed so the windowlight would go blue.
this is an unretouched still (actually a screen shot from a daily) from the red 1 shot with two lightpanel led's hand held and the practicals in the background.
For HMI's I use the blue broncolors 575 to 800 watts and have about 7, could use about 10.
We only use HMI's to mix light for daylight and I don't believe the blue HMI's really produce the best look for digital, though they have medium power draw for mains and small generators.
The only issue with broncolor hmi's is they are fragile and have a few quirks, so you have to pack them securely.
They are somewhat difficult to find and Broncolor has very little information on them, though they pack easy and are about the size of a standard flash and pack. The produce enough light for digital though
Given my preference and working in a blacked out studio, I would work tungsten only. We have two huge tungsten kits and rarely do they go out the door anymore, as they draw a lot of power, don't mix with daylight and are heavy which requires at the least C stands, the most large rollers.
Tungsten and digital to me are made for each other, as the look is deep and makes a thicker file, even though the blue channel takes a hit.
Don't discount what you can do with what you have.
This gig came in from a designer and had a tight deadline. All we had with us was one large set of photogenic monoblocks (I have about 30 of those things) and a bunch of grids.
I tried to get the mix with flash, eventually would have but the room was a trillion degrees so I shot it with the modeling lights and an old Aptus 22 on a contax.
It worked fine and actually the color is prettier than the black and white they asked for.
Maybe it's me, but light is light and the only rule is you can make a large light big, but it's damn hard to make a small light large.
In regards to the Arri's I tested them, they make a pretty light but don't have a lot of power for the costs.
But they're Arri's so they'll probably last a million years.
You mentioned you need 8 stops (that's a lot) but if you really need to go that low, cut a bunch of nd's and some slight spun, that will get you where you want and since led's don't get that hot you don't have to worry about burning through a gel.\
But my final suggestion is if you think you need 4 lights you need 8, 8 12, 12 well you get the idea.
You may only use one, but it takes crafted light to make a beautiful photography even if it's daylight and you wait for the right moment, or the lighting is beyond your control you can find the right spot.