Assume the hull form, rig design & sail plan produce somewhere near
correct placement of the center of effort & center of lateral resistance at design phase.
The factors that create weather helm
will manifest for any type of keel including multi keel forms.
In-efficient sail trim, bagged out sails
or over powering the rig would be more likely factors.
Heel angle creates a longer waterline on the lee side and a shorter on the windward. (windward hull aeration on a cat)
Lee side can sail faster than the slower windward side causing boat to round up.
Dirty bottom will make it worse.
Rig tuning and hull trim both have an effect on helm.
A sailor would likely find it easier to hit the sweet spot on a fin keel/ spade rudder
due to the more immediate feedback of the design.
The sweet spot will move with wind
, sea state and point of sail changes.
is designed to adjust the sail plan /rig to meet these changes.
The long keel will mask achieving fine focus of the sweetest spot.
Long keel will also mask the performance hit taken when the sweet spot becomes unfocused.