You should ask this question at the forum where they made this
firmware ->
http://forum.firmware-flash.com/
A friend of mine burnes 1x Princo at 2x and they work fine, i would never use 1x Princo. I hope someone answers my question to the use of 4x Princos and their quality.
It should not have done any damage to you burner, but if you are afraid of using 2x4all then just reflash it to the original firmware using the /F switch....... not /f.