Only my opinion but it depends what you want to use the bike for.Speed limit here is 70 and it's getting more and more risky to break it,your 1250 is more than quick enough to ride in this country and probably a lot more comfortable than the Busa as well at legal speeds.Even if you want to tour overseas how much quicker than a 1250 Bandit does anyone really need? And if we're honest how many of us are good enough to use that extra grunt anyway?
Being practical there's no real reason to change what you've got,having said that if biking relied on logic none of us would be riding bikes anyway.
Bottom line,if you really want a Busa buy one,personally I'd keep the Bandit and spend the money on something else,maybe a big tour of Europe or possibly a decent 250 trail bike and do a bit of greenlaning,really good fun and it dosn't cost a lot.Your choice,your money,you only live once so if a Busa is what you really want go for it.
Still waiting for answers from the Fat-Lad