Realised I didn't update this since getting the line rental switched weeks ago.
This will likely be a final update as I'm exploring the option of FTTPoD now. I had a desktop quote of around 6,500 GBP + VAT passing 22 premises if I recall correctly. Actual survey quotes so far appear to be around half desktop quote usually so I've gone ahead and paid for a survey to be done
. If it's around 2k to 3k then I'll go ahead (via Cerberus Networks) and cancel my AAISP lines. One of my lines still has an intermittent fault which I can't currently report sadly.
If anyone's interested I'll post my experience of FTTPoD.