I think that SSS is a perfectly legitimate way of providing feedback to DPS as to how they are doing. Although, it could be improved. It would be interesting to me to see a scoring system be added to SSS, SABCDE scale for example. This would provide a bit more granularity than you beat it or you didn't. Sure the % remaining when time runs out could give someone some indication of that, but it might be easier to understand for the general populace if they had the scoring scale.

I've never liked damage meters due to their tendency for exclusion rather than improvement. People typically react one of two ways when meters are brought up:

1) Advice is given for improvment, response is: Don't tell me how to play my class
2) No advice is given for improvement, just insults as to how bad someone is doing and they are removed from the group

Neither of these are particularly healthy, happy outcomes. And the rare case is advice is given and accepted graciously...