Gerco, I was trying to access:
http://multimedia-metrics.wmflabs.org/ but no luck.
There is a third choice as far as I can see (my team needs to double check me on this).
You could have a metric in wikimetrics that harvest the data you are interested on from enwiki,eswiki, arwiki databases (hopefully this is the db we are talking about) and serve that data through limn (for now).
There is some work that both of us would need to do to get this rolling but it might be a viable option.
For example:
Wikimetrics is serving here the number of newly registered users every day, that report is executed daily on enwiki, eswiki...etc and data is shown in limn (for now).
Data comes from our staging instance of wikimetrics, we will be deploying this functionality to live pretty soon: