Tbh I've put hit/stam gems in yellow sockets recently. The def cap is not really an issue since I use the def trinket from 10 man. I've dropped to only 5% hit lately and I hate seeing stuff miss. At 53% avoidance I really don't feel like gemming even more avoidance into new gear. Gotta keep the healers awake and anything that makes me not miss my avenger shield is welcome.
Throwing it at patchwerk, seeing it miss and the druid ripping patchwerk of your because you always have a threat lead with AS sucks
But I've got nearly all nax 25 man tank drops so if you're not there yet you might indeed better stick to def/stam to avoid issues with the def minimum when aquirring a new piece of gear.