you can look at it two ways;
either you are making pictures or you are making data to make pictures. If you are making pictures then you expose how you feel to make the picture you feel at the time. It might be too dark by some standards, and have no room left for playing around in post. But it would not matter. You do not intend to alter what you have made.
the other way to look at it is that you are making a negative that you will interpret later. Then ettr makes more sense. What you see at the time of exposure is not going to reflect what you intend, it will be too light or too soft.
that being said, the M8 has a lot of elasticity on the lower end compared to many other digitals of the same generation. so it tends to benefit less from ettr than other cameras. My experience is that the upper end is more compromised, I tend to protect hightlights more, iow, ettLeft you could say. there is about 1-1/3rd stop of headroom, no more.
as a comparison, the new mkIII and 5DII have more highlight headroom than these older generations, (and lower noise) effectively giving them a larger dynamic range. Ettr and benefit from lower noise on the shadow end.
In my opinion, the M8 is best shot to protect highlights, and at lower ISO's, leaving a dark preview, but you can dig it out in post (push). the detail is there because of the compression scheme they are using. Assuming you want to fiddle later.
Last opinion is that I think we should all previsualize what we want and shoot it that way, dark or light. it is hard to make everything contingent upon what you "might" want to do later.