I've got a differing view from the others. First, I agree that you shouldn't change anything right before a race without trying it out for a few rides. However, I rode Brooks saddles for a while (Swift and B17) and know something about your situation. My advice: Try a Fizik Vitesse saddle. They market it as a women's saddle in the US, but it's really more of a unisex saddle. The main difference between it and other Fizik saddles is that it is slightly wider. In fact, the width is exactly the same (15 cm) I believe as a Brooks Pro. The Vitesse is shaped very similar to a Fizik Aliante, except it is 1 cm wider and costs about half as much.
I switched from a Brooks B17 to a Vitesse Aliante. The Aliante was just as comfortable, but a little too narrow, so I tried the Vitesse. It fits me perfect, easily the most comfortable saddle I have ever used -- and I've tried many, many saddles -- and it is pretty light (about 250 g). The Vitesse weighs at least half as much and maybe even less as a Brook. I am not much of a weight-weenie, but 250-300 grams is quite a bit of weight, particularly if the Brooks is not any more comfortable than the alternative.