Enrique,
I have both the Infinium and a Quattro which is the old Safari.
If you work the treasure coast you can only detect down to the mean Low tid line so only about knee deep as the waves come in, this is due to the leases on the wreaks and Florida state law. Other locations outside of the treasure leases are wide open.
I use my Quattro in water to just above my knees, you need to have a teather on it and don't fall over in the water, I have come close. As a beach unit it is great. You will get a wicked arm workout unless the Safari coils are not bouyant, my old Quattro coil will want to come to the surface. If you plan on more dry land that water hunting you should go for the Safari as high trash areas such as parks with the Infinium will leave you wondering what is going on with all the tones. If you plan on more water hunting than land choose the Infinium.
It sounds like a Safari is more what you need.
