Hardboard under carpets

[Robbox]

Old floor had hardboard put down to overcome large gaps in the boards. After a load of plumbing work I need to re-lay the hardboard. In the landing area, the hardboard was fitted up to the metal gripper strip against the bannisters.
Hardboard is 3.2mm. Come the new carpet time, some fitters say I should lay HB up to the bannisters and have the strip on top, others say up to the strip is fine.
HB laid up to the bannisters will leave the HB edge showing, which will have to be painted and will most likely look a bit rough (HB being tricky to cut nicely).
Easiest is to lay HB up to gripper strip. Does it matter, cause a problem or be noticeable?

 

[foxhole]

Up to gripper or not, will not be visible as the carpet will cover it .

 

[conny]

I always laid up to the grippers. The back edge of the gripper, if visible, is better to paint than HB edges but carpet edge will probably cover the gripper edge.