it's all about measurement. (if you school)
i tend to ignore the 'top 10%' stuff or whatever it is and defer to kids who have been tested, but that in itself is problematic in terms of using a peer group comparison to make decisions about an individual (if you are that way inclined...).
fascinating.
gifted kids (rather than top 10% of any school, which means nowt, i'm talking about kids that have been tested and their schooling is differentiated as a result) are in some way even more enshrined in the system and being measured than their peers (and deviations from the expected norm can be judged in very different ways). to unschool would be a huge step, and i would probably suggest making a decision about where your beliefs lie prior to testing... once you are in the system (with an acknowledged 'gifted' child) then it becomes even more pervasive.
particularly if you happen upon a school that has an established programme for differentiation and some really great results! (in a standard unit of measure).
if you are going to unschool, don't assess.
that way lies madness and you are just taunting yourself, really.
embrace his individuality and go from there. units of measure are for conformists.
(i'm playing a little devil's advocate, but you know that. are you really a free spirit? or in the back of your mind do you really really want to know if he's higher than the 99.9th centile across the board????
)
what would the outcome of assessment be? say the psych says he's above average, but not gifted, what then? say the psych says, yep, he falls into the vs range across the board - how will it influence your decision with regard to schooling?
do you think kids who are gifted would be better served by school, or making their way themselves?
do you think that if you test and he is in the vs range, that you would then become embroiled in a never ending search for the perfect setting? one that is guaranteed to help him meet his potential? (using a very clearly defined measure of success, of course - like moving him ahead year groups)
let me know if you come across anything interesting.
and i'd love to hear what you decide in the end. the jury is still out here. 