The excalibur II is good with the 17 frequencies it runs simultaneously, The CZ runs on 2 (5khz and 15khz), The beach hunter 300 is really good on two frequencies, 3khz and 15khz, although it is limited to 25ft diving, so if you are looking to go deeper than 25ft, you can count the beach hunter out one out.
Weight: Comparing the CZ vs the Excal, yes, the excal does feel a lot better with the Anderson shafts over the stock shafts. These machines do both weigh 5.1 pounds, the excal has the weight on your elbow....which does help with weight and balance over the CZ where most of the weight will feel like it is on your wrist. granted you can always take the control box off and put it around your belt/neck area to save weight on your arm for both machines. The beach hunter is 5.7 pounds also with a convertable control box
Batteries: the excal takes 8 AA's over the Cz's 4 9 volts, I point out batteries because it is important for some people of which one they prefer.
CZ and beach hunter has a 2 year warranty over Excal's 1 year warranty.
excal does have a automatic ground balance over the manua ground balance the other 2 machines have. That may key in a factor as well.
All machines, after testing and trying them all work great, the largest benefit of the excal over the other 2 is the great balance for the weight and the many frequencies it runs on at the same time and the DD coil it comes with as well.
This is just an oversite of the detectors for you, if you have any specific questions or need information in a different way, ask away. I will always try to help