If you've followed Minelab or these forums for a few years, you know I am a big fan of both the Advantage and the X-Terra. The comparison you ask for is somewhat difficult, due to the inherit coil differences between the two detectors. Generally speaking, in moderate or highly mineralized ground, I find the depth of the Advantage / TS800 coil to be similar to the X-Terra with the 3-kHz concentric. I believe the TS800 (actually 7.25-inches) DD coil of the Advantage separates targets better than the X-Terra's 9-inch concentric at 3 kHz. But I believe that is due to the DD coil design versus concentric, more than the differences in the detectors. I find iron rejection better with the X-Terra, using the 3 kHz coil. Since the Advantage is 5 kHz, I attribute this more to the multiple audio tones offered by the X70 than the coil design or the detectors. All things considered, there is a lot of similarities in the manner they hunt. As I've said over and over again, if Minelab would come out with a DD coil at 3 kHz, I'd be on one in a heartbeat! JMHO HH Randy