This isn't for me, my friend asked my advice!
She already has a little girl called Emily and is due to give birth to DD2 in March. She didn't actually ask whether I thought the names went well together, just said they'd almost decided on Ella and what did I think of it. I told her it's a lovely name, but just think people will be likely to confuse the two names throughout school etc.
Hmm, don't know whether to say anything or not, she seemed so sold on Ella!