I run the SC32's and love em, have been ultra reliable, easily home servicable, but I have never had too.
If you trap the front wheel in your knees and twist the bars, there is flex, but its not a real world test, dont feel anything whilst riding.
For the weight and the travel on the DUC not sure anything comes close, and as they are not held in high regard in the UK the prices 2nd hand are crazy low.
They have an on the fly lockdown thats brilliant for climbing or if you have slapped em on a frame designed for slightly shorter travel.
My only gripe is they maybe dont have the small bump comlpiance some forks have, but that might be my SC32's rather than DUC's, I do tend to prefer my forks set slightly on the stiff side anyhow.
Someday all forks will be upside downers, like on just about any performance motorbike 🙂