I have to disappoint you but there is a meaningful possibility that you will have issues with the cheap and not so cheap ones. I am actually in the process of repairing mine (Omer Omr-1) after maybe 60 salt water dives (washed in fresh water after each dive). It has magnetic buttons (leak through the button INTO the watch is IMPOSSIBLE) but the magnets corroded due to a bad design and lost their power. Seacs you mentioned do not use magnetic buttons - there is a possibility of water getting through the button into the watch and I saw photos of water damage in those Seacs. So my suggestion would be to get something that you will be able to exchange under warranty. And use it extensively within the warranty window.
The good thing about my Omer Omr-1 - it has a rechargeable battery and a lot of issues arise when you change the battery yourself and get leaks after. In my case I do not have to do that but the buttons crapped out. Some manufacturers state that if you change the battery yourself - you will void the warranty. Sending the watch for battery change could be expensive.
By the way if you buy from Europe - it will be cheaper and the warranty will be at least 2 years. My Omer was $450 in the USA but I bought it from TradeInn for $200.
In summary - hope for the best but be prepared for the worst