Standard missed approaches require a minimum climb gradient of 2.5% if not otherwise indicated.
But airworthiness requirements for a twin engine aircraft only ask for 2.1% in CAT1 or Non precision conditions
(3 engines 2.4% and 4 engines 2.7%).
Only CAT 2/3 requires 2.5%. Therefore it makes sense to use the CAT 2 requirements for Landing Performance Calculations.
Balked Landings (Landing Climb) require no one engine out performance, only 3.2% climb gradient with all engines operative.
Therefore operators provide special balked landing procedures for performance critical airports i.e. INN.