For me the choice would be pretty straightforward. If money is not a big issue, I would suggest you get the newest EM1 ii and whichever housing you prefer. But you are looking at around $4000 for the body and hosuing alone. If you want a "deal" and want to get the 12-40 lens anyway, I would get the EM1 and the 12-40 lens from B&H Photo for $1299 and then buy whatever housing you want, but probably a lightly used Nauticam. If you don't want/need that lens and would be okay with the Olympus housing, then I would get the EM1 and the Oly housing bundle that is being offered by a number of dive photo places for about $1700.
For underwater use, I am not sure how much of an upgrade the new EM1 will be and either camera is a big step up in features from what you have now.
- Gachnar likes this