Hey Marcus,
I rode the Mana (mine) and the Whopper today which was great to jump between the two in the same conditions.
Whopper first, so stable - you'd never fall off - weight great, paddled onto small waves with absolute ease and that's with the small standard centre fin and G7 size stabilisers.......good speed in the pocket and turned on a dime, was totally impressed with the Whopper !
The Mana felt good as usual - a tad less stable but still good. Felt higher on the water - thickness felt for sure. Paddled onto waves good, did everything as you'd expect from a brilliant board.
I think if it were 1-3 foot, bumpy or some surface chop, Whopper would be the board of choice. Good waves, 3-6 foot or waves of consequence, the Mana would be the pick.
As for the McTavish, have not ridden it and can't find room for it with these two.
If your down my way (ie, Cronulla to Wollongong, welcome to ride my Mana).