Struggling with this folks, especially with the UK Football. So far I have tried Flawless Hosting, and WSS.
On Saturday with Flawless during the football it was a constant buffering session, add to that there EPG died in the middle of it all, in the end I had to use Gears, a US provider but actually worked better. Last night for the Champions League I gave WSS a try, it was worse, whereas Flawless only struggled on the football channels, WSS was struggling with every channel I tried. In the end it was back to Gears which worked pretty good with only the very odd buffer.
The problem with Gears is its main focus is US and anything else is a bonus. I can't fault there US channels, they work flawlessly but there UK and European selection is poor, in saying that they work better than any UK providers I have trialed.
I'm with Flawless too, and experienced the same issues as you described, the last few nights have been terrible a constant buffer-fest, not helped by the fact that we can't use a VPN with Flawless with any equipment which has a MAC address. Moved to FAB and it was smooth viewing, VPN works fine there on a MAG box too, didn't even have to ask to have a VPN enabled. These days its probably best to have two providers active, both paid monthly, so you can easily toggle between the two if problems occur.