Using a Nikon FX lens in a DX body?

I (might) upgrade to FX one day in the long future, but now, I shoot a DX camera.

I'm really looking to get the Nikkor 28mm f/1.8G to replace my 35mm f/1.8G DX lens. I think that it'll give me a better viewing angle than the 35mm f/1.8 and I can use it indoors without having to move much. I also like the Nano Crystal Coating that is absent with the 35mm f/1.8G DX.

But the question is that, are there any disadvantage of using an FX lens on a DX body, given that the FX lens is an AF-S (can autofocus without body's built-in motor)?

There's no disadvantage at all when using an FX lens on a DX body. However, 28mm isn't all that much wider than 35mm as you can see at this site: http://www.sweeting.org/mark/lenses/nikon.php

28mm angle of view on your camera = 45''52'

35mm angle of view on your camera = 37''24'

The FX lens should work fine on the DX body. There can be a price in money and weight for using an FX lens. Sometimes (not always) the DX lens (if there's one for the focal length you want) can have a slight performance advantage because it was easier to optimize the lens design for DX when the problem of covering the FX frame was eliminated. For example the 35mm f1.8 DX is reputed to be a little sharper than the 35mm f2.0 FX lens.

No disadvantage whatsoever, other than paying more for the lens. But, if you plan to purchase an FX in eventually, you are wise in planning for the future. Cameras get outdated, but a great lens is timeless.

No problems whatsoever. If anything the FX lens may perform a bit better on a DX body as you are using just the center (sweet spot) of the lens, and not the outer edges where most of the lens issues lie.

You are paying extra for the weight and bulk compared to a DX lens.

28mm is normal wide for an FX body. 28mm is nothing spectacular on a DX. Are you sure you aren't just getting sucked in with Nano Crystal Coating? Can you point out photos that have been shot with those lenses on a website or in a book?

Lots of people spend extra money for what they 'might' upgrade to in the future. FX is so expensive and I can never see it becoming the mainstream format for anybody but professionals and obsessive amateurs. I'm only buying FX lenses because I'm going back to 35mm.