I would choose the SSA or SSA-E if for nothing more than the full power hammer spring.
I thought they all came with full power hammer springs?
This decision is tough. I want rapid fire ability but I don’t want accidental doubles.
I would avoid the S3G and SD-3G unless you are actually doing 3-gun, or short range bullet hosing like 3-gun. IMO, it is too much of a good thing in terms of light pull and short reset. It felt like it would be hard to use consistently, without doubling/bumping it, unless you put a lot of practice and focus into your trigger control.
The SSA is a great general use trigger, and a huge step up from a Mil-spec trigger. A clean, predictable trigger with smooth first stage take-up, and a distinct 2nd stage wall that will allow a precision shot, or that can be pulled through for fast shooting. A reasonably fast trigger that can get faster with practice. My go-to trigger for a general purpose gun.
The SSA-E is essentially the same as the SSA, except with a little lighter first and second stage pull weight. The reset distance also feels a bit shorter to me as well, or at least on the examples that I have tried. The quicker reset is what IMO makes it a faster trigger than the SSA. Pick this if you really think you need the extra speed, but you are giving up some pull weight which gives a margin of safety for making deliberate shots in a serious situation.
I don’t care for the flat faced versions of the Geissele triggers. I find the original curved versions to give more consistent finger placement.
You can certainly rapid fire with the SSA-E. Before I bought my first one I had a hard time deciding between it and the SSA, like you I did a lot of researching about Geissele triggers online and I saw a lot of posts saying it was too light and to go with the SSA instead. But I decided to give the SSA-E a shot and I’m happy I did, it has about a 2 pound take up in the first stage and the a clean 2 pound break 2nd stage like breaking an icicle. It’s light, but not so light that I would call it a hair trigger, it has never gone off before I was ready. Very controllable.
I guess I’ll go SSA-E then. I just hope the reset is nice for close work.
It looks like it comes about how I had my Hi-Speed/DMR set up on my long range guns 5 years ago: 2lb 1st, 1lb 2nd stage.