Ignition if you have read and mine and kitz posts, you will see we have said once on a good endpoint the performance stays good.
The test is when you move to a different endpoint and see what happens then.
Given BTw routing is static in and around the exchange area how do you explain the performance variation based on connected endpoint?
Plusnet have even admitted now to saturated endpoints and are stating they carrying out upgrades, they wouldnt be saying this is if all was fine.
The problems are so bad, I have held of a router firmware upgrade, because I am too scared to lose this endpoint.