I am also thinking about buying one of these displays. I just sent back my Sony HS95P. It was absolutly terrible for gaming, far too much ghosting, so I don't want to be stung again.
In regards to the Hyundai (TN Panel) and the viewsonic (MVA Panel)... here's some links...
it looks like both of these panels perform about the same appart from the viewsonic has better colour reproduction due to it's MVA Panel. I don't know the cost of the viewsonic though so it could be down to price.