We have data that produces a 85:15 2-state model. As a result, the downstream correlation analysis has a dramatic discrepancy in read depth between the two states (1M:40K). I believe differences between these states are not meaningful. A high level warning to users not to overinterpret differences in correlations between states would be helpful.
It might not help our specific case, but it would also be nice to be able to pass a subsample value to afunc.fillRINGMatrix(). I'm not familiar enough with cython to implement this at the moment. I might try outputting the matrices as text files and subsampling from there.