I'd wait for a few months to see if you like the new 3861 standard edition Speedmaster. Or just purchase the 1861 hesalite Speedy Pro now, if you're not concerned about magnetism. It sounds like your long-term goal is to build a diverse collection. Within a max quota of 5 watches, the Railmaster and Seamaster 60th anniversary are too similar.
I had a SM 60th, and sold it because it was too blingy. I even satin-brushed the sidelinks on the trilogy bracelet, but that mirror-shine polishing on the flat metal ring inside the dive bezel was still blinding & distracting people in conference rooms at the office, or me while I'm driving on a sunny day. I also didn't like the rotor-spin noise on the 8806 movement. Lastly, when the bracelet was equipped, the Seamaster 60th felt heavier than a Sea Dweller. But I gather the bracelet weight won't factor into your decision making if you're enjoying wearing the Railmaster on bracelet?
On the plus side though, the dial & case dimensions on all Triology watches are excellent! The handsets are in perfect proportion with the hour markers and dial diameter, and I love the minimalist printing. The pumpkin colored lume is also great for autumn.
But you already get these benefits on the Railmaster (plus that gorgeously shaped dome sapphire crystal). I later learned that I much prefer the curved bezel design on the RM, because it's not as distracting/blingy as that mirror-polished flat ring on the SM. If only Omega made that shiny ring smaller, and increased the width of the aluminum dive bezel...
My personal preference for what to get next, given you already own the RM and JLC Master Control:
1) A 1861 hesalite Speedmaster. It can be easily converted to a display caseback, if the standard back's protruding hippocampus causes wrist irritation, or if you prefer to see the movement.
2) The upcoming 3861 Speedmaster.
3) Either the 116 or 126 Submariner. The bezel action on Subs feel really different from Seamasters. Definitely try it out if you haven't already yet done so! I won't be returning to Seamasters, until Omega improves the bezel click 'feel'.
4) Glashutte Original SeaQ 39.5. Priced closer to the Sub than the SM triology, and it's a much more compact package than either the Rolex or Omega. A good mix of features between the 2. You get chamfering and alternating finishes across different levels the case height, ceramic bezel, domed sapphire crystal. The primary downside for me would be the polished center link on the bracelet, but that can be easily brushed by a local watchmaker.
Have fun growing your collection!
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