Rating trips/outings by Class should not be confused with the overall physical effort required. Rather, it has more to do with the likely impact on the body as the result of a fall.
Disagree.
The Classes are defined more by the techniques used and skills required to climb/hike them. These techniques and skills are in turn driven by the nature of the terrain and risk. The ratings are generally a consensus for a "typical climber/hiker" doing the route--any particular party/individual may use techniques and skills from from other classes depending on his skill and fear levels.
Overall physical effort is more accurately captured in the Grade which is based upon the expected duration of a climb:
* Grade I: one to two hours of climbing
* Grade II: less than half a day
* Grade III: half a day climb
* Grade IV: full day climb
* Grade V: two day climb
* Grade VI: multi-day climb
* Grade VII: a climb lasting a week or longer
(Ref:
http://en.wikipedia.org/wiki/Grade_(climbing))
Again, an individual or party can climb a route be faster or slower than the Grade would indicate.
If there are special circumstances, they are often added in words or additional notations. For instance, sustained difficulties, exposed, possible deathfall, poor or good protection, etc.
It may be worth noting that these rating systems are consensus based--hard and fast definitions may not exist. Words may also not be able to describe the difficulty well--there is a certain amount of you have to do it to fully understand it.
You rarely hear of anyone using Class 1 (hike on established trail, no obstacles, no hands necessary) or Class 2 (hike not on established trails, or "cross-country" in Western slang).
The Class ratings are generally used by climbers and not by non-climbers. Thus Class 1 and Class 2 are hardly worth noting by those who use the system.
Doug