Hi Katrina
I expect you'll get a technically perfect answer shortly but in the meantime here's my tuppence halfpenny worth...
Whilst sequences will work from KN6500 to KN2600 they won't work the other way round.
Unless the KN2600 has the same sounds/rhythms as the KN6500 the newer machine tends to search for the nearest thing, in my experience which can be a problem sometimes.
Now transferring from floppy with KN6500 sequences on it to an SD Card I'll leave to others to comment on...
Rog