Okay, here's the thing:

When you are not lucid, you do not get a dreamy feeling. You cannot get a dreamy feeling, because, when not lucid, everything is real, no matter how odd. So, if you get a dreamy feeling, you are already on your way to lucidity, and probably don't need to do a RC at all.

I think everyone here already pretty much said that, and in much more detail, but I felt like it needed to be said again. Someone who gets lucid by reacting to a dreamy feeling was already lucid when they got that feeling; they had to be, almost by definition. So, in a sense, it makes for a lousy RC, if you use RC's as folks like Tholey and LaBerge intended (as routines you do during waking-life that you bring with you into the dream in the hopes of triggering lucidity while you're doing them, routinely, in the dream). Since everything in a NLD seems totally real and un-dreamy, doing a "dreamy feeling" RC during a NLD will likely come up blank, because everything will seem just fine when you check. Better, I think, to have a routine of checking concrete, simple things, like a clock or what's behind you.

For me, I think RC's are a daytime activity with no real use in dreams (I've never become lucid through an RC, so I may be a bit biased). They really are exercises to get your mind interested in storing the "idea" of lucidity in memory/day residue, and forming a solid, "don't have to think about it" method for taking in your surroundings for a moment and really wondering if this is a dream.

So, VagalTone, though it sounds like a great idea, a dreamy feeling really might not be a good start to becoming lucid, because you will never have that feeling before you are lucid. Now, it is a fine thing to practice, though, because once you are slightly self-aware in a dream, latching onto that dreamy feeling to gather more self-awareness is a very good thing. I do that regularly, and I would imagine that that is what Luminous was really talking about (though of course I could be wrong). And, if Luminous truly was able to recognize her surroundings as "dreamy" during a NLD, then that is a rare innate talent, and probably not a teachable technique (and yes, I would be a bit jealous of such a talent ).

Just throwing in my 2 cents, even though it seems you guys have already covered the topic quite thoroughly.