Ok... right now in my garage I have sitting an '03 SuperGSXR, an '05 GSXR 1000 (bone stock), a well modded/non boosted 2005 R1, a SupeR1, lightly modded RC51, stock Busa, and a stock 996. Yes, 7 bikes.
Anyways, here's my brief take - the busa is #5 in that group, in terms of power/performance. This is me riding all the bikes. Most powerful by far is the SupeR1, then the SuperGSXR (these two are gimmes, given that they're boosted), then the modded R1, and the stock GSXR. The modded R1 has a ported head, full Akra Evo system, velocity stacks, and a proper tune on a PC3USB. Next the stock Busa. It really just doesn't feel as savage as the new liter bikes. Sure, it's got a huge midrange, but you really have to consider the full rev range, and other than top speed, the liter bikes spank the Busa - not to mention that's easily adjusted for with different gearing. The "flickability" of the busa can't even begin to think about comparing to the liter bikes. And they've finally made the liter bikes relatively comfortable.
Pulling up the rear are the RC51 and the Ducati. And yet girls instantly love the Ducati more than all the other bikes. Just goes to show it's better to be sexy than powerful. I think the R1 wants to beat up the Duc.
Just my $0.02