Been on Virgin for about 15 years. Only really had 2 issues, one in the NTL days where I could only stay connected for minutes at a time, very tiresome when playing WoW. It just started happening one night and persisted, NTL found no fault and suggested us having a hardware fault so I dug around the internet specifically about our netgear hub and found similar issues so I downloaded new firmware and the problem went away. I can only put it down a gremlin.
The other issue was about 6 years ago where at peak times our speed would get wrecked and we'd have huge packet loss. From memory it was due to our local box being overloaded. So many people switching to VM I guess that the network was under to much strain.
On the whole it's been a legendary service so I've had no reason to want to move ISP. Downloading from Steam yesterday I peaked at 27.5MB/s, I'll have that and more thanks.