I've used Slackware Live Edition in the recent past (but not 1.3.5.1) to try PLASMA 5 before upgrading my machine to Slackware64 current + PLASMA 5.
I created a USB live Slackware with persistent directory using:
Code:
$./iso2usb.sh -i /path_to_iso/slackware64-live-plasma5-current.iso -p myhome -o /dev/sdX
Replace /dev/sdX with your own device name for USB.
Subsequently when a new version of the iso file was released, I updated the USB key after I downloaded the new iso with:
Code:
$./iso2usb.sh -i /path_to_iso/slackware64-live-plasma5-current.iso -r -o /dev/sdX
Never had any issue.