I've made life complicated for you FBF01 haven't I? The Q5 Sportback in the 2.0 TFSI form will be fine, will get you from AtoB in style. The bit you will inevitably miss is the RS 5 cylinder engine, the effortless performance, being quicker than 99.9% of everything on the road around you and of course the spine tingling howl when the RS is unleashed.
The 2.0 TFSI produces 265 bhp between 5250 and 6500 rpm and 370NM of torque between 1600 and 4500 rpm
The 2.5 TFSI produced 400 bhp between 5850 and 7000 rpm and 480Nm of torque between 1950 and 5850 rpm
1950 RPM is about 75 mph in the 7th gear in an RSQ3.
Both the RSQ3 and the Q5 Sportback weigh about the same but one has more 135bhp and, crucially, another 110NM of torque, that's the bit that provides the effortless grunt, any time any place.
A couple of images...washed the grey beast tonight - remember mine is a Std car so has the 20" wheels and silver trim, Sportback and regular have the same front end - still looks decent:
And the reason that you'd want a Comfort and sound pack....the B&O sound system and the ambient lighting . I have blue stitched seats so have opted for blue lighting too...