HI Graham,
You may be interested to know that KEF is about to launch a special edition (SE) of the IQ5 speakers - we've got an exclusive test of them in our next issue (September issue, on sale July 26th).
Sadly we haven't tested the KEF sub separately, but the Wharfedale is a five-star rated product. At this price point (around £300), we'd also strongly recommend the Velodyne CHT-8R (£300) and CHT-10R (£360), both of which we gave five stars to back in April. Subs are getting better all the time, and the Velodynes are (pardon the pun) bang up to date.
Re cabling. Ideally - so you keep the sonic signature the same all round - you should use the same cable for all your speakers. In your case, QED's Silver Anniversary (£5.50/m) would be spot on.
The only time we'd advocate using different speaker cable for the fronts would be if your budget is really, really tight - in which case we'd say prioritise the front and centre speakers (which convey the vast majority of a soundtrack) and use cheaper cable for the rears.
Clare Newsome is Editor-in-Chief of What Hi-fi? Sound and Vision