From one guy with a belly to another, m opinion is that the small amount of weight difference on a bike will mostly affect you when transporting the bike, when you're not riding it. You wont notice it while riding, unless it has excessively heavy wheels and tires, but this only if you ride someone's with a lighter wheelset.

If you like the Charge, buy it for a good price, ride it, and upgrade the wheelset and lesser components when you can afford to.