To go further with this, I have been looking for a DPS meter for some time, and I can say that I found one (maybe the only one still active) that seems to offer useful details.
It is a bit of a nuisance to set up, and to top it, in order to receive a decent read-out, it is advised to create a group of users, link them together so the parser can collect individual information from each player, combine it and display it for each player.

I will install it, and if any of you want to do the same, it would be nice to compare some data, even if we only use it to learn from it and improve our gameplay, and not to boast on who has the longest … DPS/Threat/Heals bar.