The CZ-70 is rain proof, much better on the wet salt beaches and is one of the more desirable CZ's. A really nice coin machine, hotter on silver than the MXT.
The MXT is the better prospector by a long shot, good for micro jewelry too. The MXT really hot on gold, as it is a gold detector first, and is a stellar relic machine with the massive and abundant coils available for it. It does pretty nice on coins, but I prefer the CZ for coins with the multi tone ID. The MXT has the better discriminator if you don't need tones. The MXT has 2 tones in relic mode. The CZ is much quieter hunter which is a bonus. The MXT is more sensitive hence noisier with it's higher gain.
Both a CZ and a MXT are in my arsenal. They both handle heavy mineralization very well, and are ring magnets, which is why I own them. Wouldn't give up one over the other.
You wouldn't feel out gunned with either of them. You can even prospect with the CZ, whilst not as small of nuggets the MXT can do, but the CZ gets amazing depth in adverse ground conditions on larger gold. Sub grain nuggets detection in ultramafic rock or graphitic slate ain't going to happen anyway, no matter which detector you use.
PennyFinder