What kind of handguard is on it right now? Factory 2-piece? (about 6.8 ounces I think)
I know it seems like 2 ounces might make a bit of difference, but realistically I don't think you'll notice it at all. A lighter or shorter barrel will certainly improve the handling of your rifle. As the heaviest component on your gun; this will make the biggest difference.
The Noveske NSR 7" rail is also about 4.4 ounces, and it's free float; so if the higher cost isn't a huge deal that's also a way to get less weight. (but considering the cost of the NSR, it would be a much bigger weight saving for the same cost to get a lighter barrel)
With that said, if you like the handguard for more than just the slightly lower weight; IrunGuns does carry ABarms (they only have the 10-shot AI mags that AB makes in stock) so they should theoretically be able to get their handguards for you.