I've added a hard drive to the usb on my 8900 and the video immediately starts to stutter.
I'm using CCAM which works fine - only the odd freeze, but as soon as I format the SSD Drive, press Record on remote the unit turns into a stuttering wreck!
I'm using SPARK image 1.2.64 (Apr 27 2013 update for EU) and also have S2 on alternate boot.
Stuck with SPARK as image appears to be more reliable.
If need be can switch over to S2 but I believe thats more of a fiddle to setup USB Hard drive.
Any help appreciated.