I think it's more commendable to have Big Boss at least be a different voice/person all together. Yes Hayter was practically the voice of Solid Snake. But because of that, the previous games with big boss never felt like he was his own person. Having no real disconnect between Solid Snake and Big Boss aside from eras, it always kind of irked me.
The only reason why Kiefer will take some getting used to, is because Hayter is kind of a crutch at this point.