TwinkleToes, my dd, also 4, sounds very similar to yours re reading. She is just not interested if there is anything 'formal' about how we approach learning. She started sounding out words at 2.5 and would read words that completely surprised me from time to time ('squirter' without any context to indicate what it might say at just 3 for example). But she wouldn't even dream of picking up book and reading it out loud. A couple of months ago she started reading to herself at bed time and she will now read almost everything except a book during the day. I suspect - as she has done with many things before - my dd is practicing in the privacy of her room at night and once she has reading down, she will be happy to do it publicly.
I do believe some kids are born perfectionists. DD refused to crawl or bum shuffle and started walking, holding hands with help at 7 months. Within a month or so she could have walked as well as any baby just starting to walk, but instead she WOULD NOT let go of our hand until she was 13 months old and was completely solid on her fee. She would just sit there at child care until they moved her rather than try and walk without help. Once she let go she could run, walk, jump etc without ever taking a tumble. She's followed a similar path with other things like talking and writing as well.
We've had to follow a similar process to you to show that it is ok to be wrong, make a mistake etc. She is getting there - though her favorite saying at the moment is 'I knew that' whenever it has become evident she was mistaken... hmm...
Locounu, I think a decision to test is a personal thing. We got dd tested recently because I felt pretty sure dd was gifted, but I had some doubts because of things like her hot and cold approach her reading and so on, which made we wonder whether she was gifted or just bright. If she was gifted, I knew I wouldn't have the confidence to advocate for her without being sure - there'd always be a niggle in my mind that perhaps I was just a proud mum. I'm in Australia where there aren't the same requirements to cater for gifted children as there seems to be in some US states, so this quote might not apply to you, but another parent of gifted children I know said "you shouldn't need a test result to advocate at a good school, at a bad school a test result wont make any difference". I have certainly found this to be the case in our search for a school.
Your son does sound very bright to me and similar in abilities (if not learning style) to my dd who is (to use a phrase from here that I love), HG+. I'd have to say that personally I don't think you can 'hot house' to the level that your son seems to be at. I agree with the others that it sounds like you're fostering a desire to learn. If you have a look at Ruf's levels of giftedness (if you haven't already), you might find some useful information:
http://www.educationaloptions.com/resources/resources_how_smart.php
