Originally Posted by
giggitygiggity
THR CLB/OP CLB uses a managed speed target which is whatever the CI asks for. As far as I know, THR CLB/CLB does exactly the same as OP CLB but uses the fmgc climb altitude constraints. The managed speed target remains the same regardless of whether it is open or managed climb. It will follow speed constraints in the flight plan as long as you’ve got the speed in managed.
The FCTM suggests not using managed climb unless you are flying constraints (
PR-NP-SOP-150: FMS Use).
What you said is correct. But the reason for using OP CLB in unrestricted climb is rather obvious because in CLB it will level of at constraints and ATC is not going to like that.