I had Kev's spacers and they definitly made a difference to the handling. How exactly it works, I'm not sure.

However, when a while ago, I had the suspension changed to Wilbers (rear and front), and for the front I was recommend (by somebody who knows what he's doing and I trust) to have linear springs order from Wilbers based on my weight and riding style (love the twisties), and I must say, it has made a massive difference. The front not as much as the rear (OMG, now I know what people mean when they say the stock suspension isn't all the great), but the front is definitly more "positive".
Obviously, it's dearer than the spacers.