Crossunder
Sorry you haven't had a better response!
Difficult for me to be too specific, since it depends on what fleet/base you join, but it's not a bad outfit. Rosters seem reasonably stable, pay is probably about average, routes, and types available are interesting enough, and you will fly with some very good people. Time to command is variable (if not rapid!) and will depend on which fleet you want a LHS in.
As far as links to mainline are concerned, there appears to be no 'fast track', the only concession being continuous date of joining for staff travel, and redundancy purposes.
Sorry I can't be more helpful.