Here I'm playing with the idea of allowing you to specify multiple (possibly overlapping) configs.  Right now there is just one config for Ensembles, one for Nodes, etc.  If you want to change the Ensemble config, you need to overwrite the whole thing.  This would allow you to make more incremental changes, e.g. appending some new Ensemble config settings that would coexist with the previous ones.  But that all introduces some ambiguity/complexity into the config process (e.g. resolving competing config settings), and I'm not sure if it will even be that useful?