Activate SLA targets based on any comment from an end user, or other updates

We've found that our goals with SLAs can't quite be achieved with the available targets, for the following two reasons:

1. We would like an SLA target that restarts whenever a ticket is opened for any reason (ie. response from requester, response from a non-requester/someone who's CC'd, automation/trigger opens ticket). Next Reply Time works well when the ticket opens due to the requester responding, but it doesn't treat a response from a non-requester in the same way, which means that we could miss responding to a message from a non-requester in a timely manner.
To get around this, we use both Next Reply Time and Agent Work Time, but it doesn't entirely fix the issue. If we set Agent Work Time to the same value as Next Reply Time, it handles the case where a non-requester replies, and ensures those get treated the same way, but then it ends up making some of our tickets look older than they really are since Agent Work Time is cumulative.

2. We also want an SLA target to stop any time the agent takes any action (ie. public response or internal note, or even setting the ticket back to pending/on hold manually or with a macro) 

Currently we have found that the Periodic Update achieves # 1 and not # 2, since it requires a public response to reset it, and a combination of Next Reply Time and Agent Work Time achieves # 2, but doesn't achieve # 1 perfectly as explained above. 

We would love to see some additional SLA targets added that could help achieve the above. Thanks!