Do type-2 surge protectors render type-3 protectors redundant?
The real answer is in the specific brand and model of both types you have or plan to use. Some models break down at 400 volts some as high as 800-1000 with a Courdinated system there could be Benefits to having both on sensitive / critical systems. Most homes will be fine with a type 2 but these do fail and a redundant could save that very expensive device that has the type 3 protection in addition to the type 2.