All aluminum thermostat housings and water pumps will degrade if crappy (or no) coolant is used or if super high TDS water is used to supplement it. The weld leaks on AL radiators that I have seen were from the radiator flexing and embrittlement of the metal due to the heat affected zone. For non welded AL radiators, the epoxy's used tend to fail as well. (edit, generally, it is the mounting design that is at fault in these cases. Radiators do not like to be hard mounted).
Plastic tank, aluminum radiators, get non toyota red coolant all the time. The one in my superduty (over 200K miles) has not leaked a drop. Coolant color is green..
If you want to pay for the Toyota Red, then by all means please do so. But you're not getting anything out of it..