A little bit about our gear:
As engineers, we went "slightly" overboard on planning. For example, in order to figure out what gear and luggage we wanted, I made a spreadsheet with every time I thought we would need to bring, its corresponding volume, and thus the total volume of our items by subcategory. Based on this (which came to about 60 liters, not including tools), I made another matrix of all the luggage options out there, their cost, and their size. In the end, I went with a Wolfman Large Expedition Tailbag (the "waterproof" one), expedition tankbag, and some cheap small tank panniers. I would carry tools and spare parts in the tank panniers, my DSLR and some small items in the tank bag, and the majority of everything else in the tail bag. The majority of everything else looked something like this:
3-5 days worth of food (mainly oatmeal, rice meals, nuts, and berries), a change of clothes and some layers, a cold weather riding jacket, and some toiletries, along with 4-6 liters of potable water (depending on location). I also carried a Thermarest sleeping pad, a North Face 35 degree sleeping bag, a tiny camp pot and a Coleman multi-fuel stove, and a Eureka "2 person" tent strapped to the back of the bag. On my body at all times were dirt boots, Klim pants, 661 armor, and a camelback.
Based on what I've seen here, I'd consider this a "medium" amount of stuff. I've seen guys pack 120+ liters of hard bags (although I still do not understand how this is necessary or possible), and I've seen guys run the TAT with only a small tailbag. However, to be self-sufficient for days at a time, equipped for camping at altitude and riding in all weather, and not dependant on someone else cooking our meals, I do not think we could have packed significantly less. We both took a few overnight trips prior to the adventure to tweak our packing, and we certainly learned some lessons along the way.