I personally reserve the hesalite for vintage and the sapphire for the modern iteration. The sapphire on the 3861 has underside AR coating, which gives it a whole other experience. The dimensionality of the step dial and step registers are much better presented with the AR coated sapphire. And since the sapphire is boxed, you get an undistorted and crystal clear view of the dial. The byproduct of that is you will get a halo ring in some lighting at the edge of the crystal. Big deal? No, it's hardly noticeable in most settings. It's mostly only obvious in photos.
Omega could have rounded the crystal to negate the halo ring. The issue with rounding the domed crystal and still keeping it raised is the magnification/distortion effect you will get on the dial. I'd rather not have sapphire distortion. Its quite distracting and not the same kind of distortion that you get with hesalite. You can’t see it in the photos, but the crystal also ends up having this dip in the middle. The NTTD Seamaster has it to an extend
There’s also a huge advantage to the sapphire - the exhibition case back. My friends and family, who are mostly not into watches, always get excited as soon I turn the watch over. They understand the appeal as soon as they see the engine. It’s a great conversation starter
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