The Mesmer 30 point trait in Domination, Confounding suggestions increases Daze duration by 25%, which for most of our dazes means adding .25 sec, for example Mantra of Distraction or diversion or the sword offhand daze. With CS they all become 1.25 sec.
6/6 Runes of mesmer increase daze duration by 33%, which with the known rounding should increase the above dazes to 1.5 sec with CS talented.
The talent and the runes are not stacking in pie/wvw. To test this simply film MoD or whatever with talent and runes and with just talent and slow it down. You’ll see they are both 1.25.
So the runes and talent are not stacking, and they should. Of course, just in case someone assumes, only time the dazes that don’t become stuns front the talent.