I've heard really mixed reports on them. Some seem be getting similar performance levels, and image quality... others have reported marginal performance gains, and I've heard a dozen or so people comment it thrashed their system forcing them to re-install.... others have been saying they lost has much as 40% performance.
Personally I'd pass until there is a more general consensus on the 30.30 drivers, and if your resent drivers are already doing nicely there is little reason to risk the problems some have reported with them.