BIOSMods.com Modbin/Modbin6

I just found out about this Modbin/Modbin6:

http://www.biosmods.com/download.php

Is this a good program to unhide BIOS features and get some more tweaking out of your BIOS?

What about having different dividers like 150 and 183 MHz effect a board if they weren't there by default and you unlocked them with the Modbin, could there be system problems with something like this?

Also what are the differences between Modbin and Modbin6?

THANKS