This is the first time Ive bought Cumulus ASICS, but, I have been wearing Flux for the past couple of years (same series of shoes). Seems like the 2018 models of these shoes have cramped up the toe box from previous models, so I selected the 19s instead of 20. I use them for aerobics and fitness, not running. I like the gel in the forefoot and heel, as Im not just striking heels running forward. My last pair of Flux are holding up well and not losing their bounce. I hope these are the same.