Transiting through Heathrow and their new Visa system

Has anyone transited through Heathrow since they've activated the new visa system in the UK? It sounds like you might need a visa even if you aren't leaving the airport but have to change terminals.

If that's the chase if you book a ticket that transits through Heathrow do you think the airline you booked with will be able to tell you and assure you that you will or will not need a visa just to change planes in Heathrow.

I've read where this is causing big lines and headaches since the roll out. The system keeps crashing.

I think it will be one more reason to avoid Heathrow if I'm required to get a UK Transit Visa just to change planes (because the plane I landed in, landed in a different terminal than the plan I will fly out on a few hours later).