Most modern consumer drives will spin down. Spin down can be turned off or the time set with a drive utility. This should not be an issue with modern equipment since it is designed to spin the drive up ahead of time or to wait for the drive to become available. Most WD integrated external drives will spin down as will most drives in external USB cases. The issue with WD Green drives may be that the timeout for spin down and other energy saving parameters are set too aggressively. As I recall, another issue with WD Green drives was that spin down could not be turned off on some models. These days, I'd recommend using a drive sold for NAS or surveillance use since they are designed for 24/7 operation.
The fact that Roger equipment doesn't work well with low power drives doesn't surprise me. Rogers gave me an 8642 with a bad eSATA connector and the external drive kept making the PVR reboot whenever the eSATA cable moved. That's probably the worst PVR external drive implementation I've run across. I used a WD Green drive with a Bell PVR and had no issues.