berlinonaut

Interesting - a S6Lx like your's weights 10.9 kg according to Brompton (with Brompton tires). Your's has a leather saddle (possibly heavier than stock) and an aftermarket seat post - possibly lighter than the stock model.

My 2-speed and my 6-speed are both H-models - a tad heavier than the S. The 2-speed with folding Kojaks weighted 10,3 kg when it was new. Brompton says it would be 10,4 kg. I did some modifications but it should still be in the same ballpark. Part of the extra-weight is the telescopic seat post which I am using due to my long legs - it adds ~360g in comparison to the short standard version according to Brompton.

My 6-speed has the rear-carrier, SON hub dynamo and Edelux-lights, telescopic seat post, a selle anatomica leather saddle, Brompton tires and the 6-speed has been modified to 9-speed using aftermarket thumbshifters that are a bit heavier than the stock ones. A stock H6RDx with SON and a Brooks saddle ends up at 12,3kg, according to the Brompton configurator, so the 12,x kg that I wrote sound about correct.

Steel vs. titanium is roughly 759g difference, the 8-speed adds roughly 1 kg in comparison to the 6-speed. Hence the 14,5 kg that I weighted for my stell M8RD seem to be a fit again. The 14kg mark proved to be the max that I am willing to carry upstairs, but less is highly recommended. The tiny bits and differences in component weight quickly add up. Heavier tires, blades, a rack, lights, leather saddle all add weight (or save weight if you can live w/o them).