The Triple Shiv Opener

I've been playing around with a little spreadsheet of my own devising, which I'm using to optimise my boss opening in 3.1. It seems a little weird at first, but hear me out:

Shiv > SnD > Shiv > Rupture > HfB > Shiv > Envenom

Allowing for GCD, helmet fire and a wee bit of lag (essentially mandating 1.5 sec between button presses) that puts me 10 seconds into the fight. SnD (my most valuable ability) has been up for 8.5 of those 10 seconds, and has another 21 sec to run (maximum refresh from Envenom). HfB has been up for 4 sec already, with 60 seconds to run. I've also got a 1-dot Rupture up with another couple of seconds to run. I'm running at my maximum white damage (with SnD and HfB up), low threat (no big bursts) and I've made maximum use of my combos (none left) and energy (5 left). It's also non-positional.

Opening Ambush from stealth is an alternative, but it loses me white/poison time on target (my maximum DPS abilities) unless I can start behind the boss in stealth. It also puts 2 combos into the initial SnD (wasted with the usual intent of refreshing with Envenom), uses twice the energy of Shiv (making other abilities harder to access) and generates a lot of threat. On shorter fights that might be worthwhile (maximising the damage with CB/TotT), but I'm talking about long tank'n'spanks here.

Open Mutilate? Possible, but again 2 combos get wasted into the initial SnD, it doesn't get the benefit of the "poisoned" buff from Deadly (which a Shiv opening guarantees for later Mutilates) and it uses even more energy than Ambush.

With my opening, I've got my high-value abilities up in absolute minimum time, and am pooling energy for say a CB/TotT double Mutilate to 4- or 5-dot Rupture, with 21 sec breathing room before I need to worry about another Envenom. Throw some Tea in there and I get another couple of seconds' grace.

Opinions?