I try my best to answer....
The June10 OEM firmware has lots of online TVs & online radio.
For online TVs & shows, I'd tried some, most of it works, but the problem is the SlowMax (Streamyx) which caused problem on some higher resolution shows, I haven't tried on UniFi, hope it's better. For normal low resolution TV shows, YouTube, PodCast, no problem streaming.
For internet radio, also a lot, I like the Akado radio channels
http://radio.akado.ru/I particularly like the Smooth Jazz, The 80's, Love Pride, etc
So far I have been playing every night for hours without major problem, once in a while will drop, but I suspect it's due to my network bridging and SlowMax problem.
You don't need to put any internal or external HDD, the HDPro box itself already can go internet TVs & radios
For me, definitely the HDPro entertain me a lot more and the price is very reasonable, my only wish list now is to have UniFi quickly launch at my area

Thank you very much for your answer.
With regards to internet radio, can you manually add new radio channel as it comes along ? Or we have to rely on firmware upgrade only ?
I do agree that some radio channel do need constant stream of high speed broadband, unifi should do the trick very well. I am also waiting for that service to come to PJ.