Nikon 180mm f2.8 or the new Sigma 180mm f2.8 macro?

I decided I need a 180mm lens.

The Nikon is a great lens judging from what I have read on the web.

The Sigma is a much newer lens and I have not seen much about it.

Of course, the Sigma is a macro, and it is also twice the weight (at 57 oz vs 28 oz for the Nikon) and twice the price...

I don't have a macro for my nikon camera now, so that would be a bonus, I suppose. But the primary use of the lens would be that of a medium telephoto.

Any advice?

thanks

christos