Tynan makes a good point. If you are riding for pleasure/fitness/leisure, what is the problem with the occasional puncture? I run 3 road bikes all with 23mm tyres, one with Lithion 2s, one with Gatorskins and the other with Mavic Aksions - all folding tyres. Have had 2 punctures this year in getting on for 3K miles. Changed the tubes on the road, repaired back home - no big deal. Lighter tyres WILL make a difference. A lighter bike WILL make a difference. My lightest bike is around 8 Kg with bottle cages, saddle pack etc, and is much easier on my almost 67 year old legs, especially uphill. I hope I'm still riding it - or an even lighter version - when I'm 71. Only 4 years after all! Try some lighter tyres first, and maybe test ride a lighter bike?