Cache size is generally irrelevant to functioning of Sky boxes. So it's not worth spending extra for it.
The green range are apparently the once to go for, as they are optimised for low heat and quiet operation.
If worried about noise, use the AAM tool to set the drive to quiet mode first (assuming it supports this feature).
Sorry, can not say for certain if the drive you have selected will or will not work - but hope the above helps.