sdctl and STANDBY

[JD]

I have been trying to prevent my 2 external seagate drives from
spinning down into STANDBY mode.
When I use
sdctl -c STANDBY /dev/sdb

I get

/dev/sdb: ATA  ST3500341AS       CC1H
Change mode page: failed fetching page: Power condition

I get the same error for my smaller 500GB ST3500641AS.

So, now that sdctl cannot disable standby mode in these
drives, how safe is it to resort to using hdparm, the man page
of which is full of warning with regards to disabling the standby mode.
To wit:
-s           Enable/disable the power-on in standby feature, if
supported by the drive. VERY DANGEROUS. Do not use unless you are
absolutely certain that both the system BIOS (or firmware) and the
operating system kernel (Linux >= 2.6.22) support probing for drives
that use this feature. When enabled, the drive is powered-up in the
standby mode to allow the controller to sequence the spin-up of
devices, reducing the instantaneous current draw burden when many
drives share a power supply. Primarily for use in large RAID setups.
This feature is usually disabled and the drive is powered-up in the
active mode (see -C above). Note that a drive may also allow enabling
this feature by a jumper. Some SATA drives support the control of this
feature by pin 11 of the SATA power connector. In these cases, this
command may be unsupported or may have no effect.

Would like some input from those who have actually used hdparm to
disable the standby mode.