OK, found that article. It was Car & Driver. Here it is:
Do Inexpensive Performance Meters Work? - Features - Car and Driver May 2005
If you don't want to read the whole thing, here are some quotes:
"We found the meters were off by a few tenths of a second in the worst case to a mere couple hundredths in the best case. Here, in price order, lowest to highest, is what we learned about each meter."
"With proper calibration, the Tazzo was one of the most accurate meters in the test."
"When calibrated, the Passport was a smidge less accurate than the Tazzo, but we’re splitting hairs here because the difference in accuracy works out to a measly one-tenth of one percent."
"The Passport G-Timer comes in two versions, the $100 GT1 and the $180 GT2. We tested the GT2 and decided it is worth double the price of the $90 Tazzo."