The most significant change is a “spillable” list added to CoGroup that allows it to operate on any size co-groupings.
Note there are no limitations with normal GroupBy calls as they stream directly through the stack. CoGrouping must accumulate all the groups before emitting them through some join policy (inner, outer, etc).
Also wanted to point out we have had 91 downloads since Jan 21. This is great news for such a young project.