My ds tested at 4.2 on the wppsi. He scored within the gifted range but the tester and I both believe it wasn't an accurate score for him. The tester said that he wouldn't do the easy problems but only the hard ones. She knew he knew the easy ones but couldn't give him the points for the easy ones b/c he needed to actually do them. So, b/c he didn't want to do them his score was much lower than what he should have been.
Testing always depends on the child. For some it works great when they are young and for other it doesn't. My ds just last weekend was re-tested using different test. He is now 7.9 years old. He understood he needed to do the hard ones and the easy ones. We don't have results yet but i'm hoping it will show his true numbers.