Funny you should ask. I was considering the same two units. I went with the CZ first, supposed to be great machine, well the one I got from Kellyco was a lemon, when a target was indicated, I could not get it to stop sounding so I promptly returned it after I could not get a human on the phone at Fisher. I tried the Xterra next. Much lighter unit and although a little intimidating to learn, it can be used right out of the box. I do like this unit and have been quite impressed by its depth. I recently dug up a 1/2 inch piece of some aluminum stock about a 1/16 inch thick buried at least a foot, with the 10 X 5 DD Coil on the beach in beach mode. (you should definitely get this coil if Kellyco is offering it in a package). Also found a 1/4 gram of gold in an underwater (4") bedrock crevice, it wasn't really buried, but that is a small amount to be detected.
Ok now the downside. I am on my 3rd 705, the first one got stuck on the pinpoint mode occasionally, Kellyco replaced it. The second one just would not turn on at all after 3 months, so I had to send it back to Minelab. They replaced it and the new one is working fine so far. Good luck!