The expected throughput on O2 is between 81% and 84% of sync, dependent mainly on the conditions of the particular line. It looks as though you have yours fairly clean.
The loss is basically down to TCP/IP and ATM overheads.
The WBC IP Profile system approximately takes care of the larger of those two - I always forget which and it doesn't matter for this purpose. The 88.2% figure they have chosen, with immediate adjustment, is far better than the 20CN one of huge steps with 1-5 days wait for it to update. The smaller overhead then hits that 88.2% and you end up with around the same final speed as with O2 LLU.
As XRaySpeX says, the new WBC also automatically drops lines to 3dB if they are working well, but it cannot be fixed at that in the way O2 would set it for you. Depending on your router, you do of course have the possibility of tweaking it yourself.
My broadband basic info/help site - www.robertos.me.uk
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Connection - Plusnet
UnLim Fibre (FTTC). Sync ~ 51.8/16.8Mbps @ 600m. - BQM
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