You might find that an FZ1, ZX12 or Bandit 1200 is just what you are looking for, not to mention Suzuki's new SV 1000 or the Z1000 from Kawasaki. After all, you have one cruiser in the garage, why not add a more sporting ride to your stable and enjoy more than one type of riding.
I will predict, however, that once you sample what the above bikes can provide in terms of riding fun and increased performance, you won't be asking to borrow your old bike too often.