Dwarves presumably don't get a bonus to dexterity, the rogue's primary ability score, and their "no speed penalty from heavy armor" racial ability is useless to a rogue. Trapfinding and disarming is only one (small, relative to combat) part of a rogue's duties. Sometimes the rogue will fail (especially given the specifics of trapsearching while you explore in the playtest doc, the DM rolling only once and in secret), so sometimes another party member will trigger the trap anyway. Finally, there are all kinds of traps: acid is an easy substitute for poison, as are magic arrows, pits, rolling bolders, collapsing rooms, spikes from the floor, fire sprays, and every manner of magical trap. If poison is necessarily showing up in more than, say, a third of a DM's traps, he should look at some sample traps and get some more ideas.
So, definitely not the kind of synergy I'd call gamebreaking.