I can comfirm that this works... kinda.
My scenario I used the other day was this:
Laptop (Win XP!), MKIV plugged into LAN port - neither laptop or pineapple had internet access.
I created a share via Windows.
While ssh'd into the pineapple, i mounted laptopIP/ShareName as a regular mounted folder on teh pineapple.
Scanning the waves, I was able to successfully, and easily dump data to the share, which I could see and edit on my laptop... aka i was viewing live files on windows.
So yes, you can dump over a share. As for speed, I was much too far from capacity to be able to stress test it, so YMMV