Results with irtt/flent-git. Same setup as before:

server      --      delay      --      mbox      --      client
netserver          50ms/50ms        45/900mbit

Cake config:
qdisc cake 801b: dev mbox.l root refcnt 2 bandwidth 45Mbit diffserv3
triple-isolate ack-filter-aggressive rtt 100.0ms noatm overhead 38
via-ethernet mpu 84
qdisc cake 801c: dev mbox.r root refcnt 2 bandwidth 900Mbit diffserv3
triple-isolate rtt 100.0ms noatm overhead 38 via-ethernet mpu 84

Results:
delay 100ms (rtt) flent:
https://drive.google.com/open?id=11N1QbRLJh8Akxh0iT1OKfzt7FCYutN9c
delay 100ms (rtt) stat:
https://drive.google.com/open?id=1QMaySbK5qW9IQcBZPgRSO4kNWTsQPDh8