Excellent machine, hard to beat the Tianxun TX-850 at this price point, but with the $38 add on 5" round coil the GoldFinder FS2 does seem to have slightly greater depth sensitivity on a bench test. So take that as you will, and buy the TX-850 since it comes with a protective coil cover and costs $30-50 less depending on the seller. This seller lists TX-850 for about $150 Canadian and the GoldFinder FS2 for $180 with the 11" coil alone. I'm guessing durable as well judging by the state of the shipping boxes my order arrived in. Enjoy!
Here's the boxes... GL & HH from MAER Videos YouTube!