I HAVE to use offsets with my Asus board (P8Z68-V LE with a 2500K), and the voltage is just fine (doesn't overshoot AT ALL, IMO). Try it and see, or try it again an tweak it a bit. You may have been using too high of a offset. I like having the voltage drop at idle, so I would probably use offsets even if I had the option to use a manual Vcore, honestly.
Other than that, you're looking pretty good, to me.
Also, I wouldn't say 1.25V is dangerous at idle, but why not just try to tweak the the offsets ans see what happens?