How is riding in the middle of these roads an important point? Where motorists commonly drive in an 11 foot lane and where cyclists commonly ride (at least a foot or so from the edge) would have the motorist at least clipping the side of the cyclist as they drove past if the motorist did not adjust at all. If the motorist adjusted, they obviously saw the cyclist. If there was oncoming traffic and the motorist couldn't fit by (such as would be the case for either the cyclist in the middle of the lane or on the outside edge of the lane) they would need to stop and wait for a good time to pass. Do you agree?
Helmet Head's "type D" scenario requires the rider to be in the middle of the lane. His argument is that you hardly ever hear of cyclists dying in "type D" incidents. My counterargument is that cyclists hardly ever ride in the middle of the lane, so the rarity of "type D" incidents does not neccesarily mean that riding in the middle of the lane is safer. An analogy would be "hardly any cyclists wearing green and red striped hats get run over".
Now cyclists getting clipped often (if it were true which I'm not really sure but I don't think it's UNcommon) on these roads would not surprise me at all due to the fact that a far right position encourages motorists to try and pass even when it is not safe, such as around blind corners or over hills. When opposite direction traffic appears, they take the easy way out and avoid the head-on collision by side swiping the cyclist. This is one more reason to ride centerish.
I think it depends on the exact conditions. If there's not much traffic then it's probably best to ride centerish. Unless it is an extremely winding road, especially of the type favored by motorsports enthusiasts. Then the cyclist has to take into account the possibility/probability of getting run over at the apex or exit of a turn. There is no perfect solution to that scenario, but I believe your likelihood of survival is greater if you are as far out of the way as possible. This is not a matter of visibility but a matter of physics: can the driver adjust his trajectory enough quickly enough to avoid running over you. And of course if traffic is steady, as in just a few seconds between each car, then you have no practical choice but to ride to the right. I guess my point is that experience has to be your guide, and there are no simple, one-size-fits-all approaches.