There are intangibles involved in the equations. To me, it comes down to:

1. Comfort. What you are comfortable with might weigh more than what, for example, andrewclaus, would tolerate (he also is a long-distance hiker, so he is entirely familiar with lightweight camping). I am prepared, for example, to tolerate the slightly extra weight of an Exped sleep mat than a thin half-pad Thermarest because I want to sleep comfortably. Comfort also applies to on the bike, and the best example I can think of right now is a Brooks B17 saddle which for me, when broken in, is the best; but the trade-off is that it weighs a lot more than the CF sliver of a saddle that I could put on, and probably hate after four or five days on the road.

2. What you are comfortable with comes from experience. Anyone who has done any sort of outdoor activity will have been through the mill as far as finding the gear that keeps them comfortable in all the anticipated conditions they are going to encounter. I think it is accepted among the experienced tourists that you are more likely to take more stuff with you on an overnight or weekend trip, than you are on a tour of a month or longer's duration.

3. Your interests. You may want to ride distances for the achievement, or you may want to ride to see what's along the route. Either will influence what you want and need to carry.

4. Your physical and emotional outlooks. You may only be capable to riding 30 miles a day. Others may be capable of riding 100 miles a day. Either style of touring means there is scope for different loads (and it may even be that either rider may carry the same amount of gear and be capable of completing their desired distances). Your physical capabilities may also influence the type of bike you use -- DF or recumbent -- and the speed you can travel at.

5. Money. It might seem odd, but if you are touring on a budget, and you are starting out, often the only affordable stuff is clunky -- higher-volume, higher weight. It's well known that the lighter the weight of a given item, the more expensive it is. You can pick up cheap sleeping bag that's bulky for $30 at a big-box store, or you can spend $400 on a down bag at a high-end camping store that is very lightweight and much more effective at low temps.

6. Quality of the bike. This is probably less of a problem nowadays, but noodly frames do not make good loaded touring bikes. Cycling amenity takes a hit when having to cope with a BB that moves about a lot, or the bike simply shimmies and won't manoeuvre well at take-off or fast downhill speeds.

7. Weather. You can tour lighter in warm dry weather than you can in cold wet weather. There are going to be trade-offs in bulk and weight.

8. Terrain. Flat is always going to be easier than lots of hills. Experience will tell you what you should carry in either/or sorts of terrain.

9. Your openness to the latest new-fangled do-dad that is promoted to make your camping and bike-touring life so much easier. The thing is... it often doesn't. I opted for a simple Victorinox "Survival" pocketknife rather than one that weighs twice as much and has everything so I could MacGuyver my way out of any trouble. The weight of big stuff is obvious; the cumulative effect of the small stuff is not so obvious. My jury is still out on the Leatherman style of multitool -- I just don't see too much need for pliers on a bike tour.

10. There is still that worthwhile advice for the novices -- lay out everything you think you will need on a trip, then get rid of half of it. Experience will tell you what you will use and won't use, and what you absolutely have to have for emergency purposes. Then make a list, and look critically at it after every trip. Then decide what can be done better, what can serve two or more purposes, and what can be left behind next time to lighten the load.

Where does that leave you? With a pretty complex set of equations that then have to dovetail into each other. The physics is plainly obvious, but the mathematics cannot take into account those other intangibles that make us human beings.

The most suitable answer of all, in my book, is quite simple really: It depends.