Originally Posted by
WhyFi
Going from heavier tires and wheels to lighter tires and wheels is certainly noticeable in terms of feel, IMO. Will you see any difference on the stop-watch? No.
Anecdotally, this is what you should expect to experience.
Having a lighter wheel and tire set up in general will make the bike feel a bit more lively. However you should consider the weight of the total bike as whole since disc brake bikes are typically heavier than rim brakes. IMO after switching to disc brakes on the primary bike, they tend to have a harder time climbing and less of a snap in acceleration over rim brake. However modern geometry and disc brakes make the riding experience more enjoyable overall, YMMV.
If you're only looking at reducing weight, then carbon vs. alloy doesn't matter. The primary advantage to carbon wheels is that you can get aero profiles and shapes that alloy cannot do without excess weight. Carbon wheels usually aren't much lighter than alloy anyways. You'd have to consider where and how you like to ride. My climbing bike is an older Cannondale SuperSix with rim brakes and alloy wheels for a total bike weight of 6 kg. The primary is a Bottecchia Emme 4 with Zipp 303s and that comes in at 7.7 kg.