I just weighed what I have on hand:I weighed several necks a while back.. the Warmoth are only a few oz. heavier than a Fender ,not as much as you might think . Also Slim ftw !
Warmoth = 2lb 2oz
USACG = 1lb 7oz
Mighty Mite = 1lb 10 oz
I don't know specifically about Fender. They weigh somewhere between Mighty Mite and Warmoth. But I wouldn't own one. I've never been able to get a Fender neck to play with as low an action as the other aforementioned brands.
"Just a few ounces" matters a lot when one is designing a lightweight, well-balanced bass. It become an issue of stacked tolerances: an ounce here, an ounce there, and you have a 10+ lb bass. Sticking a 2+ lb neck on a 3 lb body will be a neck-diver.

