The "hard hat" one? It's awesome if you have something between it and your forehead. I'm always wearing a beater fleece beanie if it's cold or a welding cap if it's not, so it works out. But it's still uncomfortable after an hour or two. I use it for wrenching, mostly when under a vehicle on my 2 post but it's useful for topside engine bay work, too
I have the hard hat one. It's heavy, and yeah, I probably wouldn't enjoy it for more than an hour or so, but the battery doesn't last more than a couple of hours anyway.
Pros: it lights up an entire room. Heck, it lights up my yard. I'll do gardening at night with it, and I don't need to bother to turn my head, because there are no shadows when it's on.
Cons: the flood beam is SO wide that even if I turn my head away, it still ends up blinding my wife if she looks in my general direction. It feels like it's lighting across 180 degrees. Basically, it goes well into my peripheral vision. So, I use the Milwaukee when I'm by myself, but I reach for my LED Lenser head lamp when I'm around someone else. That has more like a 100 degree flood beam angle. The Milwaukee is also quite a bit heavier than my LED Lenser SEO7R.
On that note, within the beam, both of my headlamps illuminate to about the same degree (I find them both bright enough to work with at reasonable distances, while not being so bright as to dazzle me; i.e. just right), so while the Milwaukee has a higher lumen output, I think it is only because the beam angle is wider.
Regardless, the light is very smooth, and doesn't suffer from the color fringing, banding, or strange color changes (particularly emphasizing blues and yellows) that you get from cheaper LED units.
My LED Lenser uses a lens to focus the spot beam. That gets you a much tighter beam, with much longer reach. But with my Milwaukee which has a dedicated LED for the spot beam, while the beam isn't as tight, it is smoother, and I like the fact that I can use both the spot and flood lights at the same time.