HD coverage in tennis would be incredible, but I don't know how long I have to wait for this until this arrives for tennis coverage in Germany
Anyway, I don't have a HD TV yet
In basketball it's pretty impressive though, I downloaded a half of this year's All-Star Game and it was really great. I could get used to it
I also would love to see a tennis match just for the impression, but for now, even if HD was offered, it's a hard job until you download a approx. 10 GB tennis match in HD. Not many could provide this
If you have the required hardware, of course one advantage without offering in HD would still be that a better source file also helps you making a better output file in normal resolution.