Gamespot remarked that in order to encourage interest in the part, the bass players are going to have a natural cap of 6x multiplier instead of 4x.
While I applaud the idea of spicing things up for the bass player, this seems sort of a cheesy way to go about it.
On the other hand, this will encourage really good players to take the bass part. A high accuracy performance at 6x can make a big splash with scoring.
Other random thoughts:
Does this 6x stays in effect if the bass part is a rhythm part instead?
Will it go up to 12x with star power? (if there is such a thing)
Since the bass parts are notoriously easy, will this possibly over-inflate or skew the scoring?
Is there a better/different way to make the bass track interesting?
Closing thought: The Trooper for GH2 has the worst bassline ever!