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GitHub User: bf4
ActiveAdmin helped us get up and running quickly, but once we had use cases outside of very simple CRUD, it became nightmarish.
Do read this: http://staal.io/blog/2013/02/26/mastering-activeadmin/
I did try rails_admin first because it seemed more customizable but it didn't have all the features I wanted
I'm the new maintainer of metric_fu and it should work now on ruby 1.9 without any problems. See configuration instructions at https://github.com/metricfu/metric_fu which include how you can have metric_fu load external coverage output (e.g. using simplecov)
Rcov on ruby 1.9 segfaults and fails a lot, so running it is disabled by default and the gem is no longer included as a dependency. However, you may still config it to run or load coverage stats you've already generated
Also, it works from the command-line now. Now need to bundle it or run rake or metrical
I've revived the MetricFu project if you'd like to try the newest version and submit any issues there. Under active development.