Hi Rikki, I haven't tried it with the Korg.
It does play the older Roland styles just fine. I kept the E50 partly because on the original OS the BK7m wouldn't write OTS settings, so I could do them on the E50 and use them in the BK.
Now the upgrade allows us to write OTS settings of our own.
Yes, it does have audio in, and again works just fine. You can also play recorded songs from the USB drive.
I use the FC7 pedal, and as I wrote above, it is quite useful.
It's not essential for me, because the controller has sustain pedal input and the module has an assignable pedal input.
It's very easy to change style sounds. The makeup and cover tools are great. You can instantly change the genre of a complete style, or part of a style, as you choose.
There are Technics conversions available. I don't recall if I use any of them.
DonM