Again excellent post. I will clarify that my reference to SP was only in regards to the lucidology videos. I for one never experience SP (or notice it) when doing a WILD. The only thing that seems consistent for me is vibrations. I feel tingling going through my body (or some form of vibrations) and usually from there I can form a dream scene and step into it. If I feel the tingling all over I am pretty much almost guaranteed to have a WILD. The details of what I experience as a whole during this process get blurred for me as I often dream I am doing my inductions (i.e.: i have actual dreams I am performing a WILD).

I have often wondered about the clarity of WILD's vs. other induction types and (as you say) it would also be interesting to know if the clarity of a WILD would differ if you weren't as sleepy upon initiation. People say WILD's are move vivid, but I don't really find this to be true. I have had some incredibly vivid DILDs (so much so that at least visually I think it would have to surpass waking life to become any more vivid...some people use the concept as more pixels as an analogy of how this could be possible). I have also done WILDs that ended me up in dark places or where the clarity was sub-par. Being that I think it's possible to fall asleep right before a WILD is completed and go right into a DILD, it is hard to say for sure.

I have also heard it said that you have perfect dream recall during a WILD and that it equals the same memory recall you would have in waking life. I do not find this to be true either. Maybe this is true for the guy in the lucidology videos because he swears it's 100% perfect recall. I also wonder if initiating it from SP has any affect (this somewhat points back to what you were saying as well). I've heard it said that you always experience SP but for some people they have moved into the visual process and have lost awareness of their body altogether.

To my knowledge I have only had waking sleep paralysis once. I was able to open my eyes and look around my room but I didn't see anything other than what was physically there, but couldn't move otherwise. It had nothing to do with a WILD attempt though.

You have an interesting theory about the movement signal... being tired enough where you can ignore the signal successfully. I will pay closer attention when I am really drowsy to see if there is indeed a movement signal that I am suppressing. I feel like I get the urge to move simply because I'm uncomfortable but maybe I am wrong. I even tried posting in a biology forum to see if it's possible that the mind and body are really independent and I was told this is totally wrong. Maybe because technically from a brain wave perspective you are asleep. Certainly the scientific community accepts the mind can be awake while the body is asleep or how else do they explain waking sleep paralysis and other REM disorders.