I have done both and used both for GMT and Diving.
The advantages of the Sub is more precise timing with the bezel. This is because the modern GMT bezel doesn’t have enough positions built into the bezel clicks.
The clear advantage to traveling with the Sub is the glidelock clasp can accommodate your wrist in every condition of comfort that might come up. This includes, sunburns, food allergies, wrist sprains from “kite surfing”, etc…. You just don’t know what might happen away from home and being able to quick/micro adjust to such a large range is extremely valuable.
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