I don't know how familiar you are with the beaches in your area, however, I recommend that you spend some time in the water you'll be hunting so you'll know what type of bottoms you'll be hunting over. As example, in my area here on the east cost the 10.5 is nice because for the reasons already stated, however, in the water can be a whole different issue because the bottom can be "very erratic" and not flat at all, more like buckets and heaps of sand scattered all over, bar sections and small holes and cuts. Anything over an 8" coil can be a real hassle over bottoms like this, especially when the water is a bit stained and you can't see the coil. Coil control is critical in these conditions because good coil control always you to run at a higher sensitivity VS erratic coil control that simply cause so much falsing you have to run a lower setting, sometimes much lower. Over flat bottoms the bigger coil is a plus, but over irregular bottoms it can be a real disadvantage. Another factor to selecting the larger coil over the smaller one is swing speed as the larger coil produces more drag in the water and against currents, which can really slow your swing speed down. The CZ-21 simply hunts deeper with a moderate to faster swing speed and if you slow it down too much you'll start to lose depth, especially on items such as white gold. (This is a simple fact that you can investigate yourself with a simple air test. I use a 6gram white gold man's band and a near identical 6 gram yellow gold man's band.) For all of these reasons, choosing the right coil option for your CZ-21 goes way beyond depth and coverage area.
