It would appear that DPS meters are now legal in GW2 with a number of restrictions:
I found these linked in a reddit thread:
https://www.reddit.com/r/Guildwars2/...thing/ddi7kta/We have no problems with players using a 3rd party tool whose scope is only to collect and visualize combat data gathered directly from the game client. Anything beyond that scope is still considered a violation of the User Agreement.
https://www.reddit.com/r/Guildwars2/...thing/ddi8p8y/You are correct (that memory reading DPS readers are OK as long as they are only parsing combat data). Combat data is defined as any information that is created due to the usage of skills or impact on players due to skill usage (by the player/s or an outside source).
https://www.reddit.com/r/Guildwars2/...thing/ddi9n34/We engaged in significant internal discussion about DPS meters even before we launched raids. Our discussions initially revolved around what we were going to do, but ultimately we wanted to see where the community was going.
We were not absolutely clear on our stance in relation to DPS meters because the ways they would be used (or potentially abused) was still evolving. In such a case, where we have not made a definitive statement yet are continuing to discuss internally, we did not want to take action against players until we have made our stance clear.
Now that we have set the bar and tool creators know what is acceptable, we are hoping that tool creators will make adjustments to their tools to make them compliant with our requirements and more accessible to a wider audience.
We will give our community plenty of time to make this adjustment before considering any action directly against tools or players that use them.