HMX has decided that for official DLC, they will only chart a single bass pedal. So, in RBN, there was enough of a consensus to offer 2X Bass Pedal that they came to this conclusion:
1) To release a 2X bass pedal version, there needs to be a 1X bass pedal version first.
2) The 2X chart will be the expert chart. Before that, all normal rules apply (this is why there is also a 1X version, as the expert chart for 1X won't appear otherwise).
3) All other instruments should be the same (I think one song has a minor difference somewhere between the 2 versions, but otherwise, they're identical).
So, the PS3 will never not get a 1X version, because there are plenty of folks who don't want the 2X version. Meanwhile, the 2X version experiment is still ongoing. It looks like 2X sales are down when there was a delay between versions, and 2X versions generally sold less well than 1X versions (expected), but I can only pull numbers from Rockbandscores.com, so I don't have any real sales numbers to work with (HMX does). The big question will be, was it worth it for HMX to do that (not sure how much work it took), and will it effect how songs are released in the future (as sales were hurt if songs were released separately, so they might be released together, which means you'll have to wait for songs that have 2X charts, and there might be an all metal week, which isn't popular with a lot of folks)