The New litre bikes are sh!t Hot, no arguing about it. The ZX10, the R1 or even Suzuki's own GSXR 1000, VERY well ridden will more than likely be in front of you in most circumstances accept from a dead stop or once above a 150. From a dead stop I think the Busa will prolly pull a 4-5 bike length lead and hold it for any reasonable amount of time. Also once past about 150 or so, the Busa will likely start to come around the others... But how often does this come up?
I KNow I know folks, it's freakin Blasphamy but pay special attention to the term VERY Well Ridden... This is key. Put two identical riders one on the Busa one on a ZX10, R1, or GSXR1K. Tell em' when the light turns green hammer it up to 150... The Dude on the Busa is more than likely going to own the rest, despite the better power to weight ratio of the Litre bikes, why? Simple... Bikes made to be roadrace kings are ill suited for the drags, short wheel bases and serious light weight means getting on the power is an excercise in throttle control, where on the Busa, by and large the rider can get to full throttle sooner, and keep it there for the duration... However, put the matched riders on a road course, and things are different, matched riders, the modern litre bikes are going to say goodbye to the Busa...
Put all five Bikes on a closed circuit, with lots of twisties and esses and guess what, all riders being equal the Busa is going to fall behind, it's just not designed for racing on a road course. Can it be made to handle and perform like the others? You bet, NICKSLICK is a prime example, but it really isn't the Busa's forte'.
The Busa is about being a Badass street bike, an absolute demon on the throttle, capable of handling any road you throw it's way at a High rate of speed, all the while giving the rider a comfy, relaxed, street biased ride that no other manufacterer can match.
Now, Lets head to Miami on a busa and one each of all the new Litre bikes... Guess who is enjoying the ride the most? Busa rider hands down, Freakin High Speed Super Sofa.... Busa rider hit's Miami and they're ready to continue on to the Keys, the others... Not Bloody Likely, I mean they can do it, but it is going to hurt... Now to be fair a good number of the Sub-6' club would prolly be just fine on a New Litre Bike, but will still not have the comfort level of the Busa pilot.
So, if you want the Biggest, Fastest, most comfortable, best handling open class streetbike on the road, Get a Busa. You want the fastest, baddest assed track tool yet produced? Sounds like a ZX10R, GSXR1000 or the R1.
My personal recommendation, what I would do? Is buy a Busa, Then in a year or so Find a nice 04 R1 used. That way you get the best of both worlds, until your ready for a cruiser... You know when you get all old, wore out and forget all of your ridding skills... But this is assuming your under 6' tall... My problem with the R1 is lack of space, the thing is just too tight for me... Otherwise... Who knows...
One last thought, The Busa is more than the sum of it's parts, it's everything you've ever read about it and more. Huge power anywhere, anytime, excellent handling, super stability, attracts a lot of attention (Especially the Black), it has never failed to put a smile on my face, and it has character. Thats right, I said character. Just enough of an edge here and there to remind you why you wanted a motorcycle, none of the typical "Sanitary, sterile, emotionless Jap Bike Feel" here, this one will talk to you. From the Whump and Boom of the Intake, to the vibes from that motor sitting at a lite tickling your mirrors or the Rumpty Rumpty wandering Idle, it just has more to it than whats on paper... IMHO anyway...
Bottom line, get what you want, not what anyone else tells you to get, go to the dealership, sit on the Bikes for about 20 minutes each, really get a feel for how they feel, then decide...
One last thing, do not discount the modern 600cc sportbikes either, serious fun, serious speed, easy to handle, cheep to insure, light weight, they don't eat tires, they sip gas, and all around are less intimidating enough that there is a chance you will really be able to explore their limits long before you start exploring a Litre bikes, or the Busa's... FWIW