I wouldn't expect any better performance.
1) while the banana pi has better specs, it's not as well optimized and thusly performs at the same level in most bench tests
2) the emulator community is pretty big on the raspberry pi, so the support for optimizing the emulators is there. I wouldn't expect the emulators to perform any better on the BPi.

If you are looking for better performance, I would get a cheap PC or maybe a hummingboard.

yeah, I was actually trying to talk my wife into letting me get one (but I already have 1 that is still in a closet). I think that the new B+ is perfect for piplay. It has plenty of usb and tons of GPIO!