Simple things, like on/off whether there are any possible defenders, or nil. If nil, you get the shaft, since there's no real point in raiding (from funstick pov). In any other case just make them work the same whether it's 5 on 3, 5 on 1, or 2 on 6. Bottom line is, it would help all levels across the board if the inners were more about defense and giving defenders the tactical advantage, less about being omgwtfbbq in their own right (read: spamming disrupt organ). Basic idea, that the defenders are the actual problem you face.

And well, if the defenders do not know how to play their cards, they will be just as reamed in a defense situation. You know this. A major part of cf is PK, and well, I would imagine that even though they are not very skilled at it, they will want to fight.

I remember years ago in 99 or whatever when I was still very bad at pk, I had a character named Implagur, Sylvan tiger pre shifter split. With insects and pounce it was awesome. Even though I couldn't pk my way out of a paper bag, I was very lethal. And man did I ever try everything. I bet I died at least 20 times due to insecting myself off volley when raiding empire. And chargeset unspeaks ftw! But still, I liked to fight, even if it meant that I died a lot.

Bottom line, if cabal inners would be toned down in offense, given more defense, some tactical skills, and offensive power which only fires when no defenders are in the range of the raiders.

To give you couple of theme fitting examples:

Archmage with no defenders is in transmuter or necro mode. He will either scourge, blind, energy drain, mayby throw in even forget just be major pain.
Archmage with defenders (one is enough) will turn into some sort of defensive form (with not quite as much damage reduction ofcourse), and use intercept or distract.

Destructor with no defenders will be a flurry/pincer machine bashing to boot. To be really annoying, perhaps make him pick the non-bash protected target and bash;flurry
Destructor with defenders will utilise skills like eyejab, lash, cutoff, strip and various other utility skills. Also mayby double block for the defenders? He will also target people who are not fighting to bring them into combat.

Watcher with no defenders will be in aggressive paladin mode, and do all the things it does now, perhaps with a side dish of strike of faith, and higher frequency of divine ret/light of the heavens.
Watcher with defenders would be in defensive paladin mode, using perhaps a rescue spinoff that does not lag the defender, templars mid hiltsmash etc, perhaps dish out mend wounds to the defenders.

While doing all this, the base melee would be reduced some, to make them less scary. Ofcourse there's the issue that a newbie defender recieves a smaller boon, but isn't that the way it's with all things? I bet you will get way more mileage out of an unholy blessed sword stick than most people would . Also, since most effects are beneficial targeted skills to the defending group, the progs would have diminishing returns with the number of defenders. Right now with targetted offensive progs, the progs have a diminishing returns with the number of offenders.

Damn, the more I type the better this idea is starting to look! I should just keep on going