Nick, you have to take a holistic approach to weight saving on a bike, it's all about an accumulation of small savings. I don't tend to look at shaving gramms , its a bit pointless when you weigh 90kg like I do, but I do try and look at saving the odd half kilo where possible. Carbs are heavy and they're place quited high up on a bike so if you can get lighter ones it's worth looking at. I've not compared the weight but I'm guessing the difference betwen a pumper carb and a non pumper will noticeable, especially X 2.
When you develop a race bike there comes a point when they just start to feel really nice and responsive, you can't put your finger on why they feel like this, it's just the result of careful attention to detail.
I was being diplomatic in the Classic Bike article... The ignition failure was primarily due to an incorrectly machined component and the real reason why it fell off will be revealed in the next thrill packed edition!