Well, let's start with the size of gold nuggets you are most likely to find - .5-grams - 5.5-grams. With a huge coil like the one shown, I doubt very seriously that this machine will even "hear" them. Where are you detecting? If you are in the Sudan, looking for multi-ounce gold at one-meter, then maybe - I just don't know. Most of the serious gold prospectors amd meteorite hunters I know here in the US, use either Minelab GPX machines, or single-frequency VLF machines running around 18kHz.
I guess if you are looking for HUGE targets at 1-meter of depth, that machine may work well. What have you found with it? What size coil are you using? If you are using a 14" - 18" coil, the machine may be great for gold nuggets - I just don't know, because I've never used one. The manual doesn't give me a great feeling about it though. How much is the machine?