Yes, you can use BBE+ on any Cowon D2 if you upload the D2+ firmware on the D2.
There are many guides on how to do this in the Firmware subsection (look at the stickies).
i have some resevations regarding this upgrade
1) may it cause d2 to brick?
2) can dictionary be retained in this FW. as it 2.xx. i really dont wanna lose it?
3) will there be any SQ enhancement with BBE+ as claimed by cowon?
4) any considerable improvemnts? is it really worth it?