Consider the birth year watch as mentioned above, but I’d go for a Speedmaster 145.022-74 so a stamped 1974 model regardless of when it was actually made. Only some get a Speedy with their birth year on the caseback. Born a few weeks earlier and you would have not had this option. 😉
I agree with what you're saying about the Heritage and the lack of a date window.
I was looking hard at the Rolex Explorer II (226570) with the white dial when I was in the market for a GMT, but I refuse to pay the mark-up for the name on the dial. Add to that being treated as a 2nd class citizen by Rolex ADs and it's pretty much turned me off from them forever. That's what got me looking at the GS. It's definitely a cut above. My wife joked, "You paid what for a Seiko?" and then I had to school her on the history. 😉 I'm not sure that she cared, but I enjoyed sharing. lol
How about a heritage piece? Shameless plug for one of our own. These two are gorgeous.
https://omegaforums.net/threads/omega-seamaster-300-heritage-diver-black.160085/
https://omegaforums.net/threads/omega-trilogy-seamaster-57.160059/
Any of the available heritage models are great in their own ways, and you still would have 3 watches (that grand seiko is gorgeous, btw) with date windows. IMO, the lack of a date window on the Heritage models allows for them to have a certain dial balance that's quite attractive.
From what I read of you through your post, you're looking for another diver, which I totally understand. The two only models you mentioned by name are the SMP300 + Seamaster 300.
Both of them are excellent choices. Personally I think the SMP is a little bit less classy than the Heritage, and you already have a Planet Ocean. Which way do you want to go? What makes you tick...?
A Speedy would also be a good buy. Hell, they're all excellent choices! Which one hits the spot?
