Softpedia is slow as hell, had the same experience. It was usually not your wifi connection, dl speed got down to 200k (max 400k). In that time i created a new Kanotix64 iso with PTS 2.0 on my server and downloaded it with 2.5 mb/s and got my iso faster As the live image is similar to normal U all tools should work which used to work. Like unetbootin or that tool you mentioned or you are free to write your own one - that's that i did. I do not really like that way, because i prefer hybrid iso images, but as U prefers gfxboot patched syslinux/isolinux that will not happen so soon. For benchmarking i usually boot those images via network connection and with toram option. As U kernels have got a very stupid hack included that disables HPA by default i additionally need

libata.ignore_hpa=0

It would be nice when this option is added by default because it sucks when you boot U on a raid system and then all disks fail on reboot (full poweroff needed).

https://bugs.launchpad.net/bugs/380138