As far as slippers in LE.....I interpretted it as this: As soon as bikes become eligible due to their age, and those bikes came OEM from the factory with a slipper, then retrofitting any other bikes in the class was allowed.
Maybe I am wrong?
If Lost Era is to be seen as a vintage class, then "period correct" should be okay? Being that 2003 is LE's newest eligible model year, and Kawi ZX6RR had one that yr, making it period correct to have one..... I just sold an STM, but if I were to have kept an R6, I intended to add it this yr specifically because of the ZX6RR becoming eligible this yr.