Well, im with BT, just cut a deal to reduce my bill by more than £7 a month, and only for a 12 month contract. I have never noticed any throttling of my service at all, but then perhaps i dont DL as much as you folks? That said, i really see no need at this point to consider a 24mbps, i have 6.5mbps at the moment and it does everything i could need at this time. I will wait till all the fuss dies down, then grab the fast connection at a minimal monthly increase if any.
The trick is always to claim you are leaving for another ISP, and always call on Tuesdays or Wednesdays!