Scales are fine for measuring the average flow of a pump, which is what people worry about most of the time especially with IV pumps, but they do not show up any short time scale problems.
When working with drugs with short half lives and fast operating times, such as inotropes, short term accuracy is necessary.
At a previous job we had complains that patients' BPs were varying when on inotropes, and sure enough you could see a cyclic sinusoidal change in BP. On investigation we found the lead screw of several pumps was slightly bent causing the delivery rate to vary. This was picked up with a pump tester but would not have been seen with scales.
It is horses for courses, use what you want to measure what you want.
Robert
PS I thought the other two optional ports in the IDA-4 were for watercooling of the electronics.
