Great question! s12 pro ex has extra battery (100 min runtime total) + soft roller brush vs the s15 40 min runtime... Here is my affiliate link to the s12 pro ex on Amazon: geni.us/C8Swc9
Great work! Question, with the trigger, does it click in once you pull it and stay that way until you want to the vacuum to be turned off? I recall using someone's Dyson and having to hold it in for the power to stay on (this may have just been their unit, not sure). Anywho, thought I would ask before buying. Cheers!
