So which one is better for PVP? The instant proc trinket that has better stats: agility/strenght/spell penetration or the random proc that can proc even twice in 2 minutes.
The instant proc is superior to the random proc, even if you have engineering: synapse springs that won’t stack with the instant proc.
The random blue trinket gives 912 Agility + 480 Agility (or any other main stat for our class) = 1392 Agility from the random proc + synapse springs.
The instant blue trinket proc gives 1520 Agility.
So in 2 minutes of fighting the random proc trinket can give 912 x 2 + 480 x 2 from engineering.
Or 1520 + 480 x 2 from engineering. Around 300 more Agility for the random one.
Really a small difference, however the Instant proc trinket is better in this situation since you can control the burst.
A really different choice can be for the human race as they can use a PVE trinket that stacks with the random proc trinket resulting in a much bigger burst and since if the trinkets would not stack would be a waste by using them one at the time.
So unless you have a human race character don’t try using the random proc trinket. Not even the engineering stack worths to have the random proc.