Got another clan suggestion, in case Russ finds too much time on his hands.
To promote equally matched, exiting clan challenges, how about introducing odds into determining how many points a clan gets from winning a challenge?
The odds would be determined by counting the pairings advantageous and disadvantageous rating-wise for each clan. Then, the clan that has more unfavourable pairings would get odds - if they won, they'd gain the points multiplied by some >1 number - similarly, if the clan with better odds would win, they would gain their points multiplied by some <1 number.
Probably pairings with ratings within, say 40 points could be considered to have equal chances of winning.
An example to illustrate the case:
Say that clan A challenges clan B with a four-member challenge, and the lineup ends up as follows:
Clan A vs. Clan B
PlayerA1 2010 PlayerB1 2050
PlayerA2 1640 PlayerB2 1740
PlayerA3 1495 PlayerB3 1480
PlayerA4 1300 PlayerB4 1290
Now clan B would be more likely to win the challenge, since one of the pairings distinctly favours them - thus if A would win, they'd gain their points times 1.x and if B would win, they'd gain their points times 0.y (the result would be rounded to whole numbers)
x and y would be determined by some forumula that takes into account the number of unbalanced pairs and the rating difference between them... I'd better leave it to someone more familiar with betting odds than me to come up with the formula.
This would put some welcome new spice into the clan scoring, methinks!
EDIT: also, to assure that the given odds truly reflect the real odds as accurately as possible, I suggest that the highest rating for the last 30 days be used, just like in determining qualification for rating-restricted tournaments.