Eurosport HD is very bad, its like an upscaled SD, just isn't good. BBCHD is good, not perfect, Sky Sports HD is VERY good. Setanta has a lower bitrate than BBC sports and sky sports but the encoders are the biggest problem yes.
Channel4HD have been airing alot of content in 9.5-11.5mbps recently, not the best. Ofcom should make it mandatory for all HD channels to have a minimum of 16mbps then we could have good quality HD on all channels.
Instead it looks like these channels are scrimping on cost by lowering bitrate but getting good P.R and subscriptions because its "HD".
I'll be happy with ITVHD, Channel4HD, EurosportHD coming to virgin tho even if the bitrate is low because football on itv is at such a low bitrate and quality it can be a choir to watch sometimes. Eurosport in 2mbps 544*576 is an embarrasment, especially in 4:3. Channel4 usually looks pretty decent, they dont really do sports so hard to tell how good their channel would look if football was aired on there for example.
Hopefully we'll find out shortly what the 4 new channels will be