I have a Southpaw and a Specialized on 2 KS Lev's.
The specialized is a far nicer lever blade (has a contoured section upwards towards the bar) and has a very neat SRAM mounting. I have it mounted on a Hope Tech3 lever with a matchmaker.
The Southpaw has a better range of positioning options, but needs carbon paste and a decent amount of torque to stop it moving on the bar (just on the limit of what I'm comfortable with). The lever is flatter and more square than the specialized.
Overall, I prefer the specialized lever, but in reality when riding hard I don't even notice the difference.
I had bastardized sram shifter previously, which work fine and can be set in exactly the same orientation as your right shifter. Personally I think the specific levers are much more tidy.
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