It is all very disappointing and I feel for any who may be left with interleaving after things has settled down. I was interleaved for 5-6 days after interleaving was removed. Now back to fastpath after a resync at about 3pm yesterday.
It may be a coincidence put there were two engineers around the CAB at roughly that time. After 3 days with interleaving the line had a never seen before event with 10 secs of LOM and many SES, this looked more than enough to fix interleaving in place but I am glad to say that it seems to have not have had that effect.
The loss of speed is not an issue for me, I don't like interleaving but I can't tell the difference between say 40 and 70 Mb/s except via speed test. I guess that if I had a sync less than 30 I might not be so insensitive to speed.