The idea is to have multiple timers - one for each ticket status.
This way the administrators will be able to see how much time each ticket has spent:
- before it was assigned to or taken by somebody
- in progress
- on hold or while being blocked by external parties/events
So you could see how long each action has taken.
(a total sum of each of the comments time would add up to the time stored against the ticket)
Might be worth a slight bit of a UI change to allow manipulation of the time for a reply instead of the total ticket.