i own a C0 E8400, able to Prime stable, Crysis stable for few hours at
3.825Ghz (425X9) with 1.182V.
it's true that you need higher Vcore for C0 stepping E8400 to OC.
as for 3.6Ghz (400X9) , default Vid of mine C0 E8400 will do the OC job just fine.
so to me, both of them are great overclocking gems.