I'm not dissing Kiefer, only extolling the virtues of Hayter.
I think Sutherland's doing a good job. I'm invested in him. For me, his stoicism recalls Eastwood or Bronson type characters; they say little but when they do it gives what they say more weight. I think it's only really jarring in comparison to the older games where Snake (well, everyone really) was pretty verbose.
Jesus, that's a lot of $3 dollar words...
On another note: Skullface is fucking terrifying, isn't he? His eyes really freak me out.