I like my broadband connection at home - it's with Plus.net, a local Sheffield ISP, where yours truly lives and I've been with 'em for three years.
The basic service is good, as it's based on BT's broadband wholesale network, but now Plus.net is migrating around 20,000 of its customers to the Tiscali local loop unbundled network, seemingly with the permission of the customer.
The migration away from BT's IPstream service won't affect customer's underlying BT voice lines, but it will mean that, if the user migrates away from Plus.net in the future - maybe to another ISP - the normal migration rules won't apply.
Instead, Plus.net will have to apply to Tiscali for a cease service on the line, and the new ISP will have to apply to BT for a reprovision (of broadband) on the same circuit.
The process will take around 10 days, rather than the hour or so it currently takes to migrate between ISPs.
From what yours truly can see, there's zero benefit from the move by Plus.net from BT to Tiscali's wholesale broadband service, whilst the ISP seems to benefit from the move on several fronts.
Tiscali's broadband service has not been without its problems, meaning that move also, in my humble opinion, threatens the reliability of Plus.net customers' broadband services. Allegedly :)
Incredibly Plus.net doesn't appear to be notifying its customers of the impending LLU move. The good news is that it is offering its customers an opt out of the LLU move to the Tiscali network.
It's also apparently not telling its customers about the opt-out option, either.
There appears to be no disadvantage to the opt-out, as Plus.net states quite clearly on its FAQs section that opt-out customers will be migrated to the BT ADSLMax service - with speeds of up to 8 Mbps - in due course.