With the game delayed until 2010 for Western markets, there have been rumblings that the PS3 game may see various improvements, but it's difficult to see where the developers can go from here. A lot of the accepted tricks in lowering the bandwidth overhead have already been used. For example, SEGA's developers have implemented lower-resolution alpha buffers: transparency effects are less defined, saving tons of bandwidth, but the reduction in quality is barely noticeable during gameplay. (It's a popular trick, even used by the most mighty of first-party PS3 developers.)
The crux of the matter is that the PlatinumGames team has created a game engine that targets all the things that the Xbox 360 architecture does well, to the point where it's almost as if the core development was on similar lines to a first-party exclusive. Indeed, Bayonetta is technically more ambitious than many of Microsoft's own titles this year.
As it is, the layering of transparencies, the sheer amount of them all over the screen, plus the added overhead of post-processing - it's the sort of thing that you shouldn't really be making central to the game experience in a multi-platform release, because the PS3 hardware just doesn't compete in this regard. Short of completely rewriting the game in the way that Tecmo did for the PS3 rendition of
Ninja Gaiden 2, Bayonetta is always going to have problems. Even if the overdraw (transparency upon transparency) levels were reduced, the sheer amount of effects on-screen at any given point is never going to favour the RSX.