I can understand both sides of the busa as a first bike debate. My busa is not my first bike but it is my first sport bike and my first big bore anything. It is one hell of a bike indeed and could get me in trouble in a hurry. The thing is, when you turn the key and fire it up, it doesn't just go full throttle through the gears and hit top end. It does exactly what you tell it to do and nothing more.
The real question is, as others have said, whether or not you're experienced and controlled enough to tell it to do things that won't get you in trouble. I equate telling someone which bike to buy to telling a shooter which gun is best for them. It's a personal thing and what is right for me, or Rev, or anyone else here may not be right for you.
After having my busa for a little over a month, and it being my first sport bike, the only thing I have really noticed that stands out to me is it's heft. You can tell it's a big'un when you're tooling around in a parking lot or making low speed turns. I'm sure that a lighter bike would be easier to navigate through the parking lots and such. The thing is, I didn't buy a bike to tool around in p-lots with. I bought 'er to hit the road with.
Once I'm on the road, my busa is very manageable and the riding position is far more comfortable for me than any other sport bike I sat on or rode when I was bike shopping. I ride within my abilities and don't try to ride to the busa's limits and I stay out of trouble. I say if the busa is the most comfortable for you and you want one, go now and buy it. Do not pass go, do not collect $200... Go directly to a Suzuki dealer and do the paperwork.
With that said, take it easy on a busa if you get one, ride to your limits and not the bikes, and don't ride to impress anyone. FWIW, I do kinda want a 600 of some sort to learn to wheelie on and to play with but it has nothing to do with not being satisfied with my busa. I just know that there's a chance I'll drop a bike learning to do stupid things like wheelies and I don't want to scuff the busa doin' it.
Again, the busa doesn't automatically go full throttle and top out. It does what you tell it. If you think you're level headed enough to handle your end then I say get a busa. If there's any doubt then get a bicycle.