You certainly have not gotten any Less Annoying. Cheers.

OK, HAL. Anyway.

The known benefits of using helium are not new, what Hitachi fiured out is how to keep the darn helium in the drives.

The efficiencies introduced by using helium reduce power consumption significantly per drive, even more so per terabyte, so less waste heat to transfer.. Helium has roughly 4-5 times the thermal conductivity of air, so better heat transfer.

Now, there are various things to consider here in practice, so if they published actual verified numbers, it would help. Then you wouldn't have to wonder about spin (which was a Very Good Pun, by the way). Humidity, I assume, is a controlled quantity in enterprise situations. TC varies with the temperature of the conductor. There is, as you note, a difference in the type of heat transfer (moving coolant vs. straight conduction). So there should be data plotted on curves for the normal operating temperature range and such. It wouldn't be a new thing for someone to build a worse product out of superior materials.

I think I covered, more or less, what I posted last time.

And here is the original PR:
hgst.theobviousTLD whack press-room/2012/hgst-announces-radically-new-helium-filled-hard-disk-drive-platform