UT,
Good Thread. Packing light is a fundamental tenet of my rafting style. I usually look at rigs and say, "What do they even find to put in there!?!?"
But, it's still rafting and often the impetus to optimize for weight just isn't there. I mostly hate spending my vacation packing and un-packing. I'd much rather throw everything in two small drybags, strap one to each tube, and go boating. Also, you can actually get things too light for on-water performance, particularly in big water hole-punching situations. Just sayin'. This threshold is different for every boat/oarsperson.
Here's how I roll based on trip type...
Light for fun/easy multidays up to a week, Class IV+ or less, no portaging:
IN: Chair, Rolltop, Firepan/grill/blanket, 2 brnr Partner stove with LiteCylinder (my guy still fills), croquet, small engel, small drybox.
OUT: Handwashing, extra groover supply box, tents, showers, DO,
Extra-Light for super easy mid-current reflip, portages less than 1 mile, Class V-
IN: Chair, Rolltop, Croquet, Fire stuff, Jetboil
OUT: Cooler, Drybox, Partner stove
Ultra-Light for long portages and technical Class V.
IN: Light Grill, Jetboil, not much else
OUT: Croquet, Chair, table,
Some things that have to be dealt with:
Groovers -- Forget the expensive ones. Use ammo cans and optimize size for the needs of the trip. WAG bag it too.
Repair -- Amazing what you can get done with a speedy stitch and tear aid. Worst case is really to leave a boat and have to come in again with appropriate equipment for your specific problem How bad is that? ANOTHER RIVER TRIP!!! Great excuse for the boss....
Pin-kits -- If your boat is light then it is easier to un-pin. I have un-pinned a lot of boats with the throw bag I already carry, a pulley and two ti-bloks (petzl) the pulley, tiblocks, lockers and anchor live in my lifejacket. Seriously, if your boat is light it is less likely to pin in the first place
Cooking: Jetboil for coffee and heating water. Super light grill and some aluminum foil for cooking everything else.