Yosemite NTFS support ??????????

No. OS X has never officially supported writing to an NTFS volume. It may have been possible to get it to do so, but it was never stable or supported.

You will need 3rd party software.

I've found this works well: http://www.tuxera.com/products/tuxera-ntfs-for-mac/

I'm sure there are others as well, but I don't have personal experience with them.

Apple has never officially supported write capability on NTFS drives. If you look around these forums, you can find somewhat complex Terminal commands to make it work.

But it's unsupported and undocumented for a reason - because it's unstable. As in, no guarantee you won't lose data.

Tuxera, as linked to above is one option that works. Another that costs less and is both well known and works is Paragon NTFS for Mac.

Or, if the purpose is to share data on external devices between the Mac and Windows, format them in Windows as exFAT. No extra drivers needed on either side for read/write access.

darkstar49 wrote:

I know I'd be faster off using a 3rd party driver...

But it's unfair to say Apple's driver was not stable,

Apple say it is unstable, that's why it is disabled. If you wish to disagree with them I suggest that you keep good backups.

darkstar49 wrote:

(i.e. the fstab entries) apparently worked as it should...

Apple never said that would work. It's not supported. It's not documented by Apple as working. Just because someone came up with a hack to make it work, more or less, on previous versions, doesn't mean you should expect it to work on future versions.

I see no reason to think that a degradation would be 'normal'...

Sorry. That's what happens when you come to rely on undocumented hacks. It's entirely "normal".

No. You're not. Especially since Apple never said they had one. Not for writing to NTFS at any rate. It reads it just fine. Getting it to write to it was a hack.