I've got SSA-E's on three different rifle length platforms in two calibers. The E goes with an AR rifle like peas and carrots. An absolutely amazing trigger that pays back with increased accuracy and precision aided by the lighter pull weight. The SSA-E is a superb combination with a scoped setup or hunting platform. The break is immediate. The pull weight is below minimum to use for service rifle competition so think SSA or the Geissele Service Rifle Hi Speed if that's your game.
The SSA is also an amazing trigger that is butter smooth through the first stage, albeit with a slightly heavier pull. The second stage is also a bit heavier than the E and travel a bit longer with a very fast break. I have since retrofitted single stage triggers with SSA's on my carbine platforms. I find the SSA-E a bit too light for carbine work.
I've probably installed a dozen or more SSA's for others in their rifles and carbines alike and can attest to the uniform performance.
I prefer the SSA-E over the SSA but only for use in precision rifles. The SSA is better choice for a multi-platform trigger that has to satisfy a wider range of operating conditions. A positive benefit of both is that they don't require any adjustment. Dirt simple.
One thing is certain, Geissele triggers are addictive.
Good luck with your choice.