I've just installed (full&clean) Slackware64 14.1 on a system that will be a desktop.

I let it go KDE by default and I found the following problem:

Attaching a USB storage device (my case ADATA HD710 1TB 2.5" hdd) and copying several GB of data using Konqueror (which under KDE seems to default as file manager), if I request the removal of the storage device immediately after the copy progress shows it completed will result in immediate removal of the device. (NTFS formatted).
However, the device has now a broken filesystem with incomplete files and broken filesystem structures. chkdsk repaired about a dozen errors afterwards and the data I copied was useless.

Apparently disk cache is not flushed upon removal.

If I use XFCE and it's default filemanager Thunar, and perform the same scenario, I get a wait worth several seconds when I request device removal, and I get all the data properly and no errors on the filesystem. (obviously the delay was the flushing of disk cache)

What can be done in KDE?

Wait a few seconds before removing the device?

How many seconds for 100MB worth of data transferred? And how many for 3GB?

I mean ... seriously?

I've transferred 100-500MB of usb device data and not noticed any issues using dolphin file manager under KDE, maybe there's something weird with konqueror? How does dolphin behave with your situation?