Engineering also has the following which could be of use in raiding:
1. High-Powered Bolt Gun
which does this
. According to comments on wowhead, it has a 0.5s cast and GCD which is quite costly, but could have some utility for pulls/aoe pickups/emergency interrupt. I'm not sure if there's an equivalent to Saronite Bomb
which just deals damage but doesn't require cast time or a GCD.
2. [spell]55002[/spell] has some utility if there are any encounters where you risk suffering fall damage.
As a current engineer, I'm not a big fan of the use: ability on the Deflection Plates
compared to the static armor boost from the old Armor Webbing
. 1500 Armor doesn't seem that much, so I'll probably end up macroing the use: into death strike or something like that.
I don't think you can really evaluate it as equivalent to 300 static armor because as as tank you are not just concerned with the average incoming damage but how much damage you can take in smaller periods of time in which you could die. You can't approach the deflection plates as 300 static armor because you can't guarantee the 300 armor will be there when you most need it.
If you do save the cooldown to coincide with periods of heavy damage or low health, then you aren't using it on cooldown so you can't assume 20% uptime. But - if you do save the cooldown and use it at times of danger, and it makes a difference to you not dying, it's quite useful. 1500 armor doesn't seem like much though,
I'd rather either have a bigger effect with a longer cooldown (which is probably unrealistic because it might make engineering too desirable for tanks) or a more modest static armor bonus. Perhaps the cooldown rather than static bonus fits more with the theme of what Blizzard wants from engineering.