If the problem is the overhead of making HTTP connections, surely having a pool of open connections with keepalive solves the problem in a much more durable way? This is a setup I've seen in a telecom environment that supported a good throughput.
when CouchDB is under concurrent load it does a "group commit" style write anyway and can batch nearly as efficiently as bulk docs. the only additional overhead would be the HTTP headers which is nominal when the documents are a bit larger than "hello world".
in general CouchDB does better under concurrent write load than single writer and while these kinds of optimizations on the client side can be impressive it's not actually what CouchDB is tuned for OOTB.
