Well, by the overall mass of the wood being reduced, I guess the theory is that it'll be more apt to resonate. On the other hand, some people maintain that the more mass your body has, the better the sustain will be.
I suspect that the truth lies somewhere in-between and will depend on the wood and the type of chambering done.
One thing I'd watch out for is the assumption that it will have more of an acoustic tone, which is simply not true. Magnetic pickups operate based on the string's vibration over the pickup. While the chambering will certainly alter the tone of the guitar, this will be due to changes in mass and resonance, not due to the coincidence that your guitar will likely become more acoustically audible, too.
Personally, I feel that at the end of the day, your choice of pickups, strings, and nut/bridge (plus the general combination of woods regardless of chambering) will affect your tone more than the chambering itself.
Lightness is a good thing, though, no? Reason enough for me!
Be aware, however, that while I tend to make my responses based on what I've learned, and also on common sense, I'm not an experienced luthier like some of the folks around here. Then again, all trades and arts (including luthiery) can be full of information both good and bad regardless of experience level.
Greg