Is it safe to use an off brand aftermarket grip?

I really want to get a battery grip for my D3100. But I don't know if it's safe to get a non-Nikon grip for it. Nikon doesn't make a grip for the D3100, so I'd have to resort to other companies. There's a pack with the grip and an off brand battery for $40.
Would it be safe to use?
Also, would this:
http://www.amazon.com/...004TJ6JH6/
be safe to connect to the D3100 hotshoe? I heard that if you connect non-Nikon flashes to it, it might damage the camera.
Thanks!

Added (1). Nikon doesn't make a grip for the D3100. I want the grip so I can get a better grip on the camera. The camera is kind of small and I have big hands. Also it will be more convenient to take portrait shots. If Nikon did make a grip for the D3100, I would go for that and not this off brand grip.

I guess I don't understand. Why would you take a fine piece of gear like the 3100 and cheapen it with an off brand grip? That's like buying really cheap lenses for that camera, it makes no sense to me.
Safe, probably but you never know. Nikon gear, along with Canon, is the best there's… Say with the best for the best.

From what I can see it's not a flash so it probably doesn't use any the of the camera contacts anyway. All it is is an LED floodlight that you adjust on the device itself.

Most issues I hear about non-original grips involves fast draining batteries and the lack of the second shutter release button. So far I haven't heard anyone breaking their camera because of a cheap grip. Since, you have no other choice and if you really need to, you have to get this one. A warning though. Since Nikon themselves never made a grip for the D3100 and since most non-original grip makers were one way or another formerly authorized Nikon parts makers themselves, it wouldn't be surprising to see a grip that doesn't fit your camera completely as it would have been intended for another model. I've heard some guys trimming their grips at the corners to make the edges more bearable.