Just occurred to me that I may have missed the important part of your post, Sadris. Or maybe hit it indirectly, but it's worth a direct note.

Everything in the parentheses appears to be the base rip damage. 1092*1.3*1.1 + 0.24*AP over 12sec. Naturalist and the Mangle debuff both apply after all of that is calculated.

Well you have to find out what debuffs would be on the target and how much damage they do.

If you assume mangle is up, no serrated blades or murder for simplicity, and 2500 raid buffed AP, a 5 point rupture does 130 DPS while it is on the target.

If you're knocking off a warlock dot, find out if that one dot is more than 130 DPS. If it is, total raid damage will be higher if you use evis. Your deadly poison debuff almost certainly does less DPS than your rupture, but it's likely to have better uptime on the target, so depending on your playstyle, it might be better to give up rupture than DP.

We typically field 3 locks and 2 shadow priests, but at least one of the warlocks is destruction (used to be 2 of them, not sure right now as one respecs constantly), so they use fewer slots.

Nobody has complained about their dots getting knocked off, and I use deadly poison and rupture regularly, but we only field 2 rogues, so we are using 4 slots at most for rogue stuff compared to your 6.

I guess the debuff we knock off could be anything. But I guess the basis of their complaint is doom.

Ok, on wowhead I see that CoD is 4200 damage after 1 minute, but receives 200% spelldamage, so let's say your lock has 1200 +shadow (someone tell me if this is reasonable).

That means CoD hits for 6600 damage per 60 seconds, or 110 DPS. So in this case, if you have mangle and 2500 raid buffed AP, rupture is better than CoD while either is on the target.

However, maybe CoD + your Evis is better than just rupture.

Now it comes down to the fact that you have something you can do pretty easily instead of Rupture, while the lock doesn't have a lot of options. CoD is an instant cast, so by not casting it (it's gonna get knocked off), the lock saves 1.5 sec (GCD) of cast time per minute. What will they do with the extra time? Probably shadowbolt, which is a 2.5(?) second cast when talented.

Let's say it's a (conveniently long) 5 minute boss fight, so he saves 5 GCDs for 3 shadowbolt casts.

Is your rupture damage over 5 mintues + 3 shadowbolts better than 5 CoD's + whatever you do with evis in 5 minutes? I don't know for sure how much the average shadow bolt hits for, so I'm gonna have to stop here and let someone take over. Your spec will affect the number of eviscerates you perform in 5 minutes, so that's another variable.

This is the same workaround that our guild has come up with. Its not an issue on alot of fights where one class or the other doesnt get max time on the boss but losing rupture isnt really a viable option due to the change in energy cycles. Especially when your running with 3 rogues and a feral druid ;]