G4ChordFinder or G4StepLimiterPhysics

Dear G4,

Is there a difference between G4ChordFinder and G4StepLimiterPhysics in terms of computing time and accuracy when using a complex electromagnetic field? It seems I get more realistic results when using G4StepLimiterPhysics.

Also, in the case we use small step from G4StepLimiterPhysics, it seems that we still cannot avoid setting a ChordFinder in the FieldManager. Is there a reason for this ?

Can someone clarify all that or suggest a document to read?
I am a bit lost between G4ChordFinder, G4MagIntegratorStepper, G4EquationOfMotion and G4StepLimiterPhysics .

Thanks for your help.