Windows 7 and Offline files STILL not working.

The short answer I can provide is that this has NOT been corrected in the new firmware, or at least versions 5.3.x for the Duo/NV v2 devices using the Arm architecture. Operating on my (admittedly basic) knowledge of SMB, I think the suggested changes to SAMBA on the device side and the Windows Registry on the client side have the best chance for success. But, I'd rather not enable SSH as I discovered while researching a different problem that this voids your support.

However, I'm not sure if this was an option in FrontView v1, but when configuring shares in v2 you can select to enable OPlock on the share.
So, I'm hoping that this setting also makes the other SAMBA changes listed above; fingers crossed.
But from bourney's post last year, it sounds like you can get around enabling SSH by contacting Netgear and having them do it, instead.
(Of course, the caveat is you'd have to register your device and accept whatever spam Netgear is going to start sending you as a result.)
The Windows Registry changes make sense as well, and I'd wager are necessary in either case.

UPDATE: That worked!!! No need for SSH or calls to Netgear.
I still need to do an offline test after my stuff has had a full sync, but I'm not getting the dreaded "the process cannot access the file because it is being used by another process" error when marking folders to be available offline anymore.

Thanks to all who have contributed.
Since I'[ve not seen anybody else do so, I'll post a new thread with a guide as soon as I have a chance.