Apparently, Apple changed their mind and has made some changes. With 10.9.3, LaCie external FireWire drives now spin down when my MacBook Pro sleeps. However, those connected to our iMac do not (all drives are the same model). Previously, they both worked the same way. At least now, if I follow a specific procedure, I can eject, power down the external FW drives and disconnect them properly. Previously, they never spun down, and I had to disconnect them, after commanding them to eject (they'd eject, but keep spinning).
I believe that before 10.9.3, (10.9.2 ?), the computer shutdown process no longer hung up waiting for the drives to spin down, which they never did, thus hanging up shutdown. That was particularly annoying and afflicted both the laptop and MacBook. So, there's another change that Apple made, though admittedly they had to because that behavior was unacceptable.
The drives wake up for various things, obviously foremost is when the computer wakes up. The 'put disks to sleep when possible' is still not honored.
I have noticed that, also with Mavericks, logging out of your account will remount and spin up any connected external FW drives. That is definitely different from before.
In summary, apparently Apple continues to do something addressing this and related issues. The disparity between the iMac and MacBook Pro is particularly odd, and not consistent with intending that the drives remain spinning as long as they are connected, mounted and the computer is on.
Considering the community's investment in FW external drives, they should at least return to the original cofiguration. I suspect the number of users affected by random eject is a minority. In the current condition, there are a lot more unhappy users.