I have used a BHID at a local park and found lots of coins and non-junk items. The discrimination is fairly basic with 3 tones and 3 LED light to guess at what you are about to dig(or not). In my opinion, what you are planning on using it for is the very reason to buy it....This machine sucks on my California beach in the water because of salt and black sand. Freshwater lakes it would be perfect!
I actually just got rid of my BHID to buy a PI Pro because I would rather be at the beach to hunt....
HH and good luck,
Z