When evaluating handheld RTK GPS units, prioritize positioning accuracy, which should ideally reach centimeter-level (1cm + 1ppm) in RTK mode. Ensure the device supports multi-constellation tracking (GPS, GLONASS, Galileo, BeiDou) and multi-frequency signals (L1, L2, L5) to maintain a stable fix in challenging environments like urban canyons or under tree canopies. Additionally, check the Initialization Time, which should be less than 10 seconds for high efficiency, and verify the Internal Memory capacity (at least 8GB) for storing large GIS datasets.