My 1st Suggestion is to make Dissolvent Poison be able to hit everything like it was on Turtle before its change.
2nd is to make Poisons have AP Scaling
Currently the management of changing poisons is a drag in raid and in the world.
Examples:
1) If you are farming Twilight Elementals for Crests you have to change Poisons due to elementals being immune to Instant but humanoids being immune to Dissolvent.
2) Nature Immune targets not listed on Dissolvent EG: Green Dragons
Then while Poison Rogue currently does good DMG, that DMG is flat and does not scale and the spec will fall off as more and more gear becomes available.