This is my only gripe about the Brooks B17 -- the weight! I'm in the process of putting my touring bike on a diet for long-distance (brevet) riding. This bike fits me really well. I read somewhere that the Fizik Aliante is basically a modern version of the B17. So, the chances are that if you like the B17, the Aliante might actually work well, too. Fizik has several versions of this saddle to choose from, some as light as 200 grams. I am in the same boat -- I find it really hard to pull the trigger on the Aliante, esp. after coming back from a long ride and realizing how well the Brooks B17 has worked for me. I personally would not consider another Brooks (or any other leather saddle brand) if saving weight is the main goal. They are simply not made for the weight conscious, IMO.

Hopefully someone with more experience with the B17 Vs. the Aliante (or another much lighter saddle) will chime in.