The Nexus multiport is a thing of beauty, and is the only option available that offers AF, MF, and A/M Switching underwater with this lens.
I used the 70-180, courtesy of Craig, in Dominica and was impressed with its versatility. He was right on about zooming to enhance composition, furthering your discipline as a "crop in the camera" photographer. I always used the lens with a 5T on the lens, and for closeup stuff added a Nexus wet lens. With the 5T, the only shots I missed were of some finicky reef squid that hovered right at 31" away, and wouldn't let me get closer
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The 105 w/ a 2x Teleconverter is a specialized tool that is NOT AT ALL versatile, but can accomplish some amazing magnifications for a super macro style of shooting.
In my book, these are two very different lens combos for two very different types of shooting.