Look no further...
http://www.wiggle.co.uk/felt-f85-tiagra-2014/
Beautifully finished, sensibly spec'd, made in the USA and not the far east, and a joy to ride. An £800 machine for £499.
Also rode the Ribble too, and while it was comfortable and fitted me well it was dynamically the worst bike of the lot. Quite an old fashioned frame, basic tube manipulation, no tapered steerer, and it showed.
Approx 30"I am 5'10 and ride 54cm frames. I would think it'll be too big for you without amends and too big bikes are often bad news...I'd go for the smaller one unless you are very long in the torso for your height (what's your inside leg measurement?)