The simple answer is that, at this point, I don't know for sure but it looks like BT 4.0 is the implemented solution for the device in all V1.0 manufacturing iterations other than, maybe, very early manufacturing.
The Benjie BJ-T6/AGPtek Rocker V.1 uses the CSR8811 chip which is capable of handling both BT 4.0 and BT 4.1, depending on the software stack implemented.
I was reviewing original/early manufacturing units of the BJ-T6 and Shenzen Benjie was telling me, at that time, they were implementing BT 4.1 on the hardware, which is why I link 4.1 rather than 4.0 data sheets.
Shortly after I started writing my reviews, AGPtek got international distribution rights and started indicating in correspondence to me that the device they were selling as the Rocker was, in fact, using BT 4.0 CSR. Maybe the Benjie engineers had some issues and reverted to 4.0 to expedite getting the product into scaled manufacturing.
AGPtek subsequently released new firmware, but these releases do not seem to be touching the system kernel. Only UI, file compatibility and directory structuring changes are noted in their release notes, so I have to suppose that BT 4.0 is what is implemented on virtually all V 1.0 BJ-T6/Rocker DAPs available in the marketplace.
Anyway, to make things more interesting, Benjie is now manufacturing a newer version of this DAP and at least the AGPtek Rocker version has the firmware up to Version 2.0. However, I would hazard a guess that, based on early descriptions, the component hardware is still the same and only the case and firmware have changed.
I don’t have the 2.0 version in hand and am not staying in touch with Benjie, so if you are considering a purchase you should contact Benjie if you are in China and AGPtek elsewhere in the world to get a read on what the current specs are.
If you do, please post updates/comments here and consider writing a review that will be more current than the one I wrote last year!