Some of the reviews I read suggest that, in comparison with the 9.1 they're a little less capable in the mids and lows but I think that might be ideal with a good sub and centre?
The reviews of the 9 are like reviews of the Paradigm Atom vs the Paradigm Mini.
The 9 is tinier than the 9.1. It still reaches 80hz for a proper crossover. No matter what...the 9 now, paired with those Aiwa for rear duty would be an immediate improvement.
Then you can decide later on another pair of 9...or then step up for 9.1. The Wharfedale center will be the tough one. Even used, the 9cs still commands the same price as new.
I'd happily grab 4 9.0s and a centre just now and find a good sub as time goes on. My big issue is getting clear dialogue while maintaining body so I feel investment in the centre is worth while.