So it would appear that as long as you can reforge out of hit/exp into haste, it could be benefitial to gem full exp/hit/haste over str? It would be a bit risky because 2 haste is only slightly better than 1 str, and you can't always reforge perfectly so there's always risk of losing more stats than gaining. Also, losing a lot of str could cause haste value to drop below 50%.
As long as you can hit/exp cap from gear alone you should because then you are trading the weaker haste/crit/mastery for stronger hit/exp/str (can't get str from anything but gems). Besides, at the T14H level you can't reforge out enough hit to do that anyway.