A spreadsheet is probably going to be your best friend in this situation. Many of them have options for which rotation you will be using, mostly with/without Rup, and they generally assume having 100% up-time for SnD. Not many combat spreadsheets would include using Env over Evis simply because the damage loss from either a) dumping your DP stack or b) sometimes having to wait for DP to get to 5 stacks by the time you have the CP for it. Another thing to keep in mind when you are testing is to remember whether or not you have spec'd and glyphed into Evis and/or Rup (points in or out of Imp Evis vs. Blood Spatter). Also, if you are using the build I think you are using, those last five points (in Vile Poisons and Imp Poisons) are meant to be determined by your gear and a spread sheet, not necessarily the 1/4 split most people just go with.
Personally, my best rotation/spec is talented and glyphed Evis. Priorities are SnD (start with 2 or 3 points depending on Glyph of SS procs), SS to 5 CP, Evis, rinse and repeat. If SnD has less than 6 seconds remaining I refresh it (not a terrible idea to let it run to 0 and pool energy as long as you don't violate the next tip). Try never to be energy capped, use KS only when you will not cap out (and also only when you have SnD running because you do still auto attack during KS).
What is the difference between ignorance and apathy? I don't know and I don't care.