I think you're right, mm. Unless alternates are brought into the mix, it looks like just us 3 legends, so Champ speed is guaranteed for all Foursomes (AltShot) and Singles matches (unless I end up against either of you in singles) as they will indeed be ranked matches (with default tees).
However, as Cerino asked too, the Fourball series will have to be set up as practice mode, and I'll have the answer on exact conditions for that very soon (but since it will be practice mode, they cannot be Champ greens!).
EDIT: I forgot about Jack (cricketrules), so it looks like both teams have 2 Legends (and there are several more amongst the alternates lists)