Should I still use entitycache in Drupal 7 projects?

I have been using entitycache [1] without problems in D7. However I have not really measured lately does it really improve the performance and is there some issues? And what is the state at the moment about entitycache going to core [2] in D7 or D8?

What I am asking is:

1. Should I use entitycache in projects of any kind? (Like using APC cache ALWAYS because it does not matter is there logged in users or not.)

2. Has anyone measured the impact lately? (If it is in core it does not really make sense using it, right?)

3. Can someone contribute some rough statistics / analytics what is the impact of using entitycache?

[1] http://drupal.org/project/entitycache
[2] http://drupal.org/node/597236