As far as I'm concerned, rupture does not improve proc chances, nor add stacks.
From what I've gathered, the direct damage increase, especially with the Vial trinket (Heroic), is far greater. From my recent tests, even on the current stage I have, 43k on Ultraxion, with rupture it's 39k. Seeing as how rupture uptime is going to be lower, what's the use of it. And having the extra 6% on Evis still outweighs the already high SS crit chance.
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