I have been looking at this topic over the past week, and from what I can find, JASO FB, FC & FD all have the same lubrication, but FD improves exhaust smoke & carbon deposits. Husqvarna semi-synth LS+ oil is FD despite being only a semi. $14 a litre roughly.

As a side note, I have been reading a 1978 paper that was arguing for a standardised system of measuring 2 stroke oils. They proposed a garden standard (using a mac chainsaw for measurements), a motor bike standard (using 180cc Vespa) and a outboard standard (using yamaha something).

Might have to start a 4 stroke oil thread now to discuss car oil v SAE 30 mower oil