Double tripple pass are for constant high RPM stuff like NASCA or SCCA kind of stuff.
Tube size mostly depends on radiator style. Top flow works best with smaller tubes. The cross flows work better with larger 1' to 1 1/2" tubes.
The main reason is the top flow radiators need a restriction to help prevent coolant at higher RPMs frome running a path of least restance from the inlet to the outlet and basicly bypassing a majority of the radiators cooling area.
The cross flows dont have the same issue it has to flow from side to side. So the flow restriction isnt needed. Increase in flow allows more water to be exposed to the cooling area and sent back into the engine.