The BK9 is amazingly light for a 76, and they didn't sacrifice the keybed action, either! I guess not having a touch screen, speakers, or an old boat-anchor floppy disk drive pays dividends in terms of weight!
The BK9 also has a sequencer (which the E-A7 does not.) They are a little hard to find and still holding their price because of it. But unless you need the multipads I give it the edge over the E-A7.