In reply to chummer:
> The most important thing is that the grades are consistent within a wall.
I couldn't agree more. Many people do most of their indoor climbing at a one particular wall, and use the grading system to try to assess their progress as they work on improving their strength, stamina and technique. It is therefore incredibly frustrating when the grading of routes is inconsistent, or varies over time.
It's far more important to me that the grades are consistent rather than whether they are harder or easier than other walls, or outdoors, or whatever.