I have the central led and a makita rechargeable 13w fluorescent, and have had a series of those yellow corded 13w fluorescents. Since their output and form factor are similar to the "bank of led's" in question, this input might be helpful.
The problem with the flourescents, and thus likely the bank of led's units, is that they always seem to be tough to get in position under the car, and their output seems to be glaring in your face as much as it is at your work. You can have a blinding, more lumens than the sun setup and light up the whole bottom of the car, but you know what? You still can't see up into the nooks and crannies where you're working, and it's worse dealing with too much light. I like less light but easily directed. Also, the central's small head leaves you just a small lens to clean, those others have a big plastic lens that in my experience doesn't stand up well to oil, grease, etc, as well as the degreaser you use to clean your tools and all the goop out of your hair. They quickly get brittle and break.
You may also consider those safety glasses with attached leds. We don't use eye protection on certain jobs we should, and lying on your back looking up a stuff we have to remove that's covered with oil, tar and road grit, is certainly one.
The headlamp sounds practical but every time I think of one I realize how goofy it looks having a light point everywhere you look, my neighbors would think I was nuts. Until it broke I wore an energizer headlamp around my waist!
