i started water hunting with the bhid, with the original floater coil. I hear the 300 coil is near neutral. anyway, I tried a sock with sand and it was flopping around. And the added weight was a pain on the wet or dry sand.
The coil also has a problem flipping up, especially in surf. I found that reversing the coil helped with both problems. Much less coil movement, and as the angle my body made with the coil was more acute, I could hold it down easier without added weight.
The lights do indicate what's down there pretty well, and they work in all metal, though bottle caps can show green light. But the deeper targets, the discrimination falls off, so deep targets are pretty much dig it all. It also discriminates by sound, with 3 tones.
It is sensitive to small items. It does go deep. My first outing where I had everything set up right including a good scoop, booties, and wet suit (winter time in s. fl.), I found a Tiffany friendship ring in the water, a 9k english men's gold ring with nice heft, and a silver toe ring. The gold ring and the toe ring were under the seaweed that piles up at the highwater mark. The gold ring was at least 12" deep, or more. I went out 2 days later and found a large men's ring with 3 diamonds, total about 1 carat, the diamonds were of indifferent quality, but it was 14k, solid, and heavy. I found more gold, too, in a few subsequent trips.
But when I found an excal 1000 selling cheap, I jumped at it. It is much easier to use in the water over longer periods of time. The bhid is noisier in the water, and that darn bhid coil tires me out, hurts my hands like carpal tunnel, and the excessive noise in the headphones is also tiring.
However, it is much cheaper than the excal, and it does works good at finding gold. The BH 300 may be much easier to use, I don't know. But the price is getting up there where you might as well get an excal.
I think I'd like to have the bhid for the wet and dry sand more than the excal as the coil is much lighter, but then a DFX might be better for that.