I created blank image(DMG) with diskutility. because , diskutility says there is no index etc for iso. after creating DMG and restore the dmg from iso. it takes less time to restore the USB from DMG.

I didnt have time to try , but I will give information about it.

I have question in my mind, i will try this with SB700 Chipset and sometimes , some distros waits to recognize USB and sometimes it can cause problem and it does not recognize and just stop.

I will give you feedback related to USB booting for Distros.

Thanks nfoav8or