Lots of thoughts on the ER 301 in this thread 
I like the idea of these types of modules. Although. there comes a point where a combination of an Expert Sleepers ES3/6/8 and a laptop with MaxMSP is more accessible for my programming skills.
I was always intrigued by the QuBit Nebulae. It seems that the most recent firmware on it can run PD patches which might be interesting.
http://www.analoguehaven.com/qubitelectronix/nebulae/