I also have a WTB saddle on my mtb. I opted for the Speed She, and I'm pretty happy with it.

It's light and comfortable, and the "love channel" works as well as a cut out for me (I'm in the Terry Butterfly camp). It also gives me a lot of room to get off and behind the saddle for descents.

My only complaint is that the trim/decals are wearing off very quickly. The first time I laid it down, I was wiping off decals along with the mud!