Yes, if you know what to do with a result. If you happy with 28-56mm on aps-c and don't want to invest your time into learning post processing, buying a Sigma is way, imho.I'll try to rephrase it to make myself clear. I'm sure getting just Sigma 18-35 1.8 will benefit me. What I'm wondering is whether investing another 800-1000$ to get either 80D or go 6D with a lens around 800$ (to match the price of 80D and Sigma) would provide another big/considerable improvement in IQ.