Vallon+Tallon are only going to be great if you can get two rogues each deploying them. Pants poison is the right thing nearly all the time; you can bust out the TDS ones when you want a lil' edge.
I use two, The Vallon+tallon Like Brohg, but I always have sloth poison too. Since they stack its nice to have that slow.
The question was "group" poison. Vallons and Tallons are raid poisons that are really only of benefit if you have at least two rogues using Vallons and two using Tallons against the same target. If you're using them in group content (which I assume you are if you're using sloth), you're just wasting them. For group content, using your pants poison as your primary damage poison is the best way to go unless you enjoy farming/buying relic fragments for mana poison. The utility poisons can be helpful for odd groups/molo play. For those, you'll be using the Tainted level 100 mats.
