The closest hunting ground for me the local community park that I can walk to. Since it's so close, I probably have hunted it twice as many hours as any other place. It has your typical tot lots, swings, ball fields and wide open spaces, along with a community beach. It dates back to the 1930's as a park, and before that was part of a farm back to the 1700's. It is loaded with iron. There are old square nails, horseshoes, farm relics everywhere except for the beach. But even worse are the pull tabs and aluminum shrapnel. I flat guarantee that every swing of any detector in the open areas will get you at least 4 aluminum hits and at least two iron hits. The aluminum only goes down about 4", but the iron goes deep. Plenty of clad, also in that top 4". Between 4" and 11" there are all the Wheaties you could want, a few Indians and scattered silver. I've pulled two nice gold rings from that park in the past year as well, and a few gold and silver pendants and such.
I started hunting that park with the AT-Pro. In 6 months I got lots of trash and lots of clad. A few interesting iron farm relics as well but not one wheatie and no silver. But there was just too much masking of the deep good targets for the AT-Pro to be successful. I had great results with the AT-Pro in less trashy areas though.
The first time I hit that park with the CTX I pulled two mercs, a 1960 quarter and 13 wheaties in about three hours. I had never pulled anything like that with the AT-Pro in hundreds of hours. I really didn't know the CTX at all at that point, but I was blown away at how I was pulling those old coins in the same hole with nails and tabs. 6 months later with the Deus, I had similar results at that park.
I bring all this up just because you mentioned that you hunt fair grounds and other iron infested, trashy areas that are likely just like this. I just want to assure you that either way you go, you are going to be totally blown away. In that type of ground, the difference compared to your AT-Pro is going to be stunning. You really can't make a wrong decision with the two choices you are looking at. If you are a technical geek like me who loves bells, whistles and color screens, go with the CTX. If you want to swing easy and fast and pack light, get the Deus. Either one is going to get you smiling.