Durano and Kojak are certainly lighter and aimed more towards going faster but that doesn't guarantee anything.
I have a reasonably light 20x 1.35 Primo comet and a not-so-light 26 x 1.5 Primo comet kevlar on my SWB. Both are lighter than the Marathon Plus, though. Which doesn't guarantee I'm riding any faster than you are.
__________________
Bacchetta Giro A20, RANS V-Rex, RANS Screamer