I have a variety of tyres. 35 and 28 Marathon Plus, don't punture, even after nearly 15 million metres! Seriously! I have Conti GP4000 and Grand Prix 4000s, both never puntured (all spring/summer use though so far). Finally I have a couple of Conti Sport, the ultra budget tyres which you get free with any new racing bike (as they're dead cheap). Never punctured after a couple of thousand kms. I run the tyres near their max recomended pressures!
I guess either I'm lucky, or something else? I'm now on Marathon Plus for winter, and Balders, that extra weight, really doesn't make any difference! Weigh yourself, add the bike weight, with panier, and then see what percentage Marathon Plus make to the overall weight! Its very low! Plus this 2Kg?? This is the overall weight of the tyre, not the extra you get in changing from Gatorskin to Marathon Plus.
Oh and I received a Wiggle email today, they have a deal on some tyres just now.
http://www.wiggle.co.uk/red-hot-tyres/?utm_source=1063gb-34-fri&utm_medium=email&utm_campaign=sep&utm_content=gb-27-09-13