It depends, doesn't it. If the aircraft is so un-safe that without this equipment it shouldn't be flown, then the entire fleet should be grounded until either a) it is made safe or b) taken out of service. If the aircraft is safe enough to fly as is, then it is safe enough to fly. Collisions happen, regardless of equipment fitted and procedures followed. It sounds from this thread that the equipment would be at best, a tiny increase in warning capability and likely increase the risk of collision due to desensitivity to warning alarms.
So is the aircraft safe enough or not?