Re: BT Infinity installed
I've had BT Infinity (plus VM 50) since late 2010. BT Infinity is fine 38/8. Peak times slow down to 25/7 sometimes. Latency is steady but it starts at a higher base than VM's latency. Certainly better for MW3 gaming than VM.
When my area gets Infinity FTTP 100/30, I'd have to think hard as to whether or not I could justify keeping the VM circuit.
My advice is at your risk.