Some 4.0 stats are not backward compatible with those of 3.0 xdcr's

xdcr stats can be accessed through the following rest api:

/pools/default/buckets/[bucket_name]/stats/replications%2F[target_cluster_uuid]%2F[source_bucket]%2F[target_bucket]%2F[stats_name]

For some stats, the stats name used in 3.0 xdcr and 4.0 xdcr is different. For example, "docs_latency_wt" in 3.0 is changed to "wtavg_docs_latency" in 4.0. Since the same 3.0 name, "docs_latency_wt", is being used in 4.0 documention, the name change seems to be an oversight rather than intentional design and needs to be undone.

Following is the list of name changes that need to be undone:
docs_latency_wt -> wtavg_docs_latency
meta_latency_wt -> wtavg_meta_latency

The following stats are in 3.0 and not in 4.0 stats. It may be better to add them back:
docs_latency_aggr
meta_latency_aggr

Following stats is suspicious:
time_committing -> time_committing
the 3.0 doc says that it is "Seconds elapsed during replication.", while the 4.0 stats measures that time spent creating checkpoints. Need to confirm whether those two stats are really the same thing.

3.0 stats:
http://docs.couchbase.com/admin/admin/REST/rest-xdcr-statistics.html

4.0 stats:
http://developer.couchbase.com/documentation/server/4.0/rest-api/rest-xdcr-statistics.html