Actually I was told by someone at Apple that you are supposed to get more 8 and 10 bit uncompressed streams than you are DV because it actually takes more computing power to play back a compressed format. The reason being uncompressed formats have a constant bit rate which is easy for processors to compute. Compressed formats such as DV, DVPRO, and DVCPRO HD actually take more processor power because bit rate varies.
let me know if you have seen different, may be Apple is wrong
Kevin Ritchie
Editor
Cubist Post & Effects
Philadelphia, PA