You make valid points, Niner, but in the end all the potential issues you listed can be solved through improved engineering. For instance, the uniformity of the magnetic field between Helmoltz coils is dependent (among other things) on the coils being perfectly identical and perfectly aligned. It's obvious we know more today about making coils accurately and precisely positioning them than we did when we first invented the electromagnet.
I figure once artificial gravity gets out of the scientists hands and into those of engineers, the devices will be gradually improved. Same way we improved lasers and optics to go from the CD to the DVD to the BlueRay disc (steps which required mostly manufacturing improvements to a technology that essentially remains the same).
Bobscrachy, I did think of slowing time using extreme gravity to achieve stasis. But I'm not sure if it would work that way : as I understand it, the kind of time-slowing effect we see in movies involving (say) black holes is not due to the gravity of the black-hole itself, but to the fact that objects around black-holes inherently have very fast orbits. So time slows down not because you're experiencing a lot of gravity, but because you're travelling at utrarelativisitic speeds (above 30% of the speed of light)
You COULD reproduce the effect without a black-hole, though : in the Forever War, Joe Haldeman describes people flying their ship in circle, at ultrarelativistic speed, so they could live long enough to wait for the return of loved ones (which could take centuries). In this scenario, you'd use artificial gravity for propulsion, so that you could accelerate to the right speed quickly enough.
Needless to say, there's a lot of problems with this concept, such as finding a circuit in space where you'd be reasonnably sure you're not gonna hit debris : at these speeds they'd be unavoidable AND deadly.
Lunarsolarpower : Wow
now that would be awesome. I'm trying to picture in my mind the kind of device(s) and infrastructure you'd need to create your fortress. I think we're looking (at the very least) at a spherical array of gravity generators in orbit, the failure of any single one of them leading to the Earth getting blown to bits. You know, so far Earth has known a lot less catastrophic failures than what man alone has triggered
If anything we engineer could be 100% safe, though, I think this would be great. But we could just as well use our knowledge of gravity to deflect anything that comes our way, perhaps towards the Sun. Your idea is nice because, of course, we wouldn't need to aim at anything. But you'd still have to be able to make exceptions of, say, space ships, so it's not really less complicated.
I think I'll rather go with land-based anti-celestial-body doomsday weapon. Turn the Earth into a Death Star.
Jaydfox : read about Lagrange points. It's really like a tug of war, gravity doesn't exactly work like magnetism. Say you have two identical cars and link their rear fenders with a chain, then have them move in opposite directions : the cars won't go anywhere, neither will the chain. In what we're discussing here, the chain would be your body's atoms, the cars would be gravity sources.
Nefastor