They did, but as a competition only bike only, any registered one has been done in hindsight
The s is the off road, road legal one
The e has a bigger carb, slightly better head, plastic tank and no lights or clocks. And a bunch more horsepower. (And no kickstart tim, that’s an option that can be fitted to all three)
E version is also road legal. I believe what Boris described was the K model which isn’t road legal or very common.
E has the better carb, aggressive cams and bigger exhaust diameter. The S was released to be duel sport, whereas the E was for off roading, the SM is obviously.