first off, I doubt you really ever got more than 10lbs of thrust from a ducted fan, no matter what the manufacturer says.

secondly, the turbine has a tailpipe velocity on the order of 400mph while the fan had maybe 200mph.
the exceleration and performance is very noticeable. I could never fly my AV8R at 17lbs ready to fly on my field with a fan, would never have happened, but my 13lbs turbine yanks it off and straight up.