Yes, that is quite a relevant question. I've been thinking about this in the context of my next Uganda trip, sometime Feb-mar next year (planning process and team building already under way; for a 5-6 day trek in the mountains and 4-5 days safari, with a day or two slotted in for car transit, with photo opportunities along the way). So far, on my past trips, when I took the S2 with me, I usually travelled with just 2 lenses (35 & 120, 35 & 70 or 70 & Hassy 210) and tried to fit everything in a Billingham 307 bag or a smallish Crumpler photo rucksack. For the upcoming trip, I am thinking 35/120/210 plus a Gitzo cabon tripod with Arca P0 head. Although we'll be using porters during the trek part of the trip, we/they will also be hauling a tent, sleeping bags, food, fuel etc. Each porter can carry max 18 kg. Also need to bear in mind airline baggage weight restrictions on the way there and back. So part of me is thinking M9 plus 24,50,90,135 (maybe RX1 as back-up), the other is thinking S2 with the above lenses, even if they all go just in separate Tamrac lens pouches in a normal 30 litre day pack (no photo bag); same for all spare batteries, filters etc. Not decided how the body would travel; looking for some simple pouch, something like the Artisan & Artist pouch for 3 M lenses, just bigger. Maybe RX1 or M9 with 35mm lens as back-up and for taking snaps during the steep uphill sections where the S2 around the neck/shoulder would be just too much of a PITA, based on past experience. Anyway, still some time left to ponder. The thing about the S/S2 is that when you've organised a major trip, found time & money & companions, you want to bring the best equipment. Every time I hesitate, I remind myself how Ed Viesturs and his team hauled an Imax camera to the Everest... Then again, one needs to also think about enjoying the trip, not just about the camera (I think Umberto Eco has a point when he says that he no longer takes a camera when he travels, because he wants to experience the world first hand, and not through a viewfinder).
By the way, nice photos and write-up on your website.