Is USB 3.0-to-USB 3.0 data transfer between two Linux OSes possible?

Yes, USB 3.0 makes full duplex data transfer possible, with 3.0 cabling. The specs are in section 5.5.2 of the USB specs. The link to those specs is given earlier in another answer. http://www.gaw.ru/pdf/interface/usb/USB%203%200_english.pdf

Cables are becoming easier to find- they can be bought on Amazon, for example, for under $8.00. be sure to buy DATA TRANSFER, male A to male A cables. Newer versions of Linux support the transfer.

I hope that helps someone- I searched for the answer for quite a while myself.