I haven't read all six pages, but I'll throw in m .02.
Once you "flip the switch" you have done several things:
1. Given up the advantage of surprise, with the exception of the split second where the actual light comes on.
2. You have most likely illuminated yourself to some extent
3. You have given away your approximate if not exact position... Light switch placement is pretty standard everywhere you go. If the bad guy wants to get you, now he just shoots at or near the doorway.
4. Unless you're going to stand at the light switch and work it like a 5 year old, you have completely given up control of when there is light and when there is not.
Granted, 1-3 also apply to using a flashlight, but #4 is the game changer. As a LEO and low light instructor, we teach our guys to use their lights as little as possible while searching for a suspect. When they are used, it is light on 2-3 seconds, light off, MOVE technique (Same concept as "I'm up, they see me, I'm down" bounding movements for those with military experience). In one's own home, a light really shouldn't be necessary at all until the intruder is verified and you've completely got the drop on them. I won't be giving up ANY of my weapon mounted or hand held lights any time soon.
And fiddletown has brought up the best tactic for dealing with an intruder... Let them come to you. Then hit them in the face with a tactical light and proceed with whatever course of action is necessary.