good machine and kinda puts the others you mentioned to shame , the T2 is one I have heard good thing about for hunting iron laced sites and relic hunting , but if you are also gonna venture to the beach occasionaly then the clear cut choice is the sovereign Gt. It does have a slower reset speed than some you mentioned but it is a killer on deep old coins, the cortez has some seirous limitations, the dfx is good but I have seen it fail miserabely in a demo / iron setting .havent seen the Cz7 in action but did see the cz5 this weekend and it is an iron magnet ........ I would go sovereign or teknetics for for what you describe, with the edge going to the Sovereign ......the t2 will choke up on the beach without a doubt .....and keep in mind that this info is based on some experience and a lot of listening to what others have said .....I personally only have experience with the sovereign elite, not the Gt but it is realitive the same(with a few new features) from what I was lead to believe but I did personally witness the dfx choke hard in a iron infested demo ....