I am a week or so from purchasing a brand new Giant XtC-1. The stock bike seems sweet enough for me, but I'm tempted to make a few customizations: switching the Hayes Stroker Ryde disc brakes for Cane Creek Direct Curve 3 v-brakes; replacing the 9-speed cassette with a 6-, 7- or 8-speed cassette (Who makes quality 6- and 7-speed cassettes?); and adding Shimano XTM760 hubs in place of the Formula 32H disc hubs.
I've been riding an older Giant with v-brakes and a 6-speed cassette for the past eight years and manage to get along fast enough, so I figure upgrading those parts on a new bike would work out well. It would, by my math, take the total weight of the bike from 29.3 pounds to about 27 pounds.
Bad plan dude- the 9 speed cassettes aren't heavier, your 9spd shifter wont' work on the 6-8spd, and in the end it's not likely that those 2 pounds off of a 29 pound bike would even be noticeable. If you want to do something that will really change the feel and lose weight, upgrade the wheels and tires.
why not try riding the bike first and see why other people seem to enjoy having more gears and better working brakes in all conditions. quit focusing on the numbers so much and figure out what works in the real world as opposed to on the scale.
more gears may not make you faster but is is nice to be able to ride a comfortable cadence than to be stuck between two gears, especially one that is sitting on your workbench. the same thing for the brakes