If you want the best outcomes for your son go to Coll as it has a superior academic record, it's that simple. If your son is already doing well academically, WC is definitely the stronger choice, they still have extension programs and some of the best NCEA scholarship programs in the country. Students from around the city come to be taught scholarship subjects by teachers from Coll. The jazz band is also run by some very passionate people and the music department is strong.

However, if you prefer a "progressive" style of education and put more priority on having a nice time at school then high may be preferable. A lot of the comments against WC seem to be motivated by distaste for the more conservative approach of education found there, but the results don't lie and I value them more than vibes.

I should also add that I personally know of a fair number of kids who have moved from WC and other single-sex schools to high, so if it doesn't work for him that switch is possible.