I started a thread a long time ago with a link to a company that manufactures intercoolers in Oz.
The same side inlet/outlet intercooler is better the shorter it is - the first 25% of the core after the inlet gets 80% of the flow.
For maximum efficiency, an inlet and outlet diagonally opposed is better.
Small turbos with high boost need longer core dimensions with less height than bigger turbos with either less boost or the same amount, which should use shorter core length and more height. Using height for measurement perpendicular to the direction of air flow and length as the length of the core the air is traveling through.
I would expect that for drag racing, the most efficient intercooler would be wanted (for all-out drag racing and air/water setup running through dry ice), but for street use, minimizing volume, hence the same side inlet intercooler would be more responsive. Combination of less volume and less bends in the tubing.
Everything is a compromise.