The center is pretty good. I've got no issues with it.
I would be using 4 NS-F310's and 4 NS-B310's. F310's for front and rears, B310s for front and rear presence.
I've been looking for better for less but haven't found any.
I would like to have all 9 speakers from the same series so this limits my selection.
I'm not against replacing the center...
Remember the Highway Men (Simon and Simon?)with the remote controls and the semi that turned into a helicopter?