Hugh has good questions. Truth 1253, I'd see if I could get hands on testing of both or either or any machine before you buy it. I see so many used machines of all kinds for sale, you know there is a lot of bought it on hype purchasing and then found dissatisfaction with the machine, no matter who makes it, so it gets sold. Been happening since machines were first made. I've even done it, albeit a long time ago. I keep my Deus set on the idiot mode, (factory settings) and it has been awesome. I have used it in open fields, moderate soil, did good. Parks and salt beaches with lots of aluminum foil, did good, was able to discriminate out the foil and small trash. I sometimes deliberately dig pull tabs, just in case there's gold hiding there, but have yet had the machine misidentify gold for a pulltab. In CW hut sites, I deliberately dig the bigger iron, yet got a nice cuff eagle button with a ton of iron still stuck to the back, an iron backed one on Sunday. Was a solid signal. In the CW huts I can easily get through the nails to the good stuff. In house sites, I hear the iron, sometimes dig the big pieces as these are colonial homes and I might get an ax, and it gets tiny 3/8" pewter and tombac and brass buttons and the coins. Is there anything else I want or need? No. I have found out the 74 khz setting on the Deus ROCKS with small brass and silver items down, like WAY down in the ground. Pulled an eagle cuff button at 9" plus the other day. Thought I had missed it but no, like, it's way too deep, but it was at the bottom of the hole. The 28.8 khz frequency didn't pick it up. Equinox goes to 40 if I remember correctly.
I would see if there is a club near you, join up and see what the people are saying about their respective machines before you buy anything. Might be able to get that testing in.
Here's one example, went digging in bad ground and was using my trusty Tesoro Cibola. Was getting nothing but new bullets. Other guys were getting minie balls. So I switched to the Tesoro Vaquero with a large loop and started nailing them, as in 50 minies. And both machines are from the same manufacturer.