Hello again! Sorry for the late reply.
Starting from the end, yes I have considered m4/3. Thing is though that while my uw photo skills can definitely improve I also feel the technical limitations of my current setup. Sure, it doesn’t go wider than 24 mm (equiv), but it’s also a matter of sensor performance. And the LX100 is not that far off a full m4/3 system in a sensor performance perspective. Thus, upgrading to m4/3 would feel like… not a big step enough. See, I’ve upgraded in small increments a couple of times before and soon wanted more. So this time my plan is to take a deep breath and go modern full frame.
Mind you, I’m not saying you are wrong about the luggage. But last time I travelled with a friend who has does full frame Ikelite with two DS-161 and a large-ish dome, so I hope I’ll be able to manage. (I’m primarily looking at Sea & Sea or possibly Nauticam, with YS-D2 strobes.)
Yeah I might end up with the 16-35. It would annoy me, but the cost for that lens is a small part of the total system cost.
I had or have hopes for the new Tamron 17-35/2.8-4 (F-mount), which seems like a good lens topside, and smaller and lighter than the Nikon 16-35. As such I could justify owning it for other reasons too. Unfortunately I haven’t seen any underwater testing of it yet.
The Tamron 17-35 isn’t stabilised, but that might not matter much underwater? At least not as long as strobes are used. Possibly another thing if taking photos in available light in murky Swedish waters.
The stabilisation thing ties in to the “which camera” question, but I think it may be better to devote a separate thread for that.
Back on topic: it’s not really as if the next trip is necessarily very important, but I’m thinking about going on a dedicated wide angle photo trip/workshop, and if I do I would like to have upgraded. Also, with time photography has become an important part of my diving’s recreational value, and even if the equipment is way more expensive than a single trip it somehow feels wasteful to go with equipment I’d rather upgrade. Still, I want this upgrade to be well-judged since it’s such a lot of money at stake – it would make a sizeable hole in my savings account.
Luckily I still have a couple of months to consider options. But after that I need to decide whether to take the plunge this year.