hmmm... good points to you both.
I would still prefer something less complicated though and try to meet a bit of flavour.
Hmm here's another little idea that just popped up for flavour. just an idea lads so I need feedback ÂÂ
Blood rageIf a World Eater Berserkers formation loses an engagement they will always elect to abandon their transports in favour of getting to grips with the enemy in hand to hand combat rather than run away. Therefore, the WE player must elect to destroy his transports
rather than force his berserkers to withdraw (refer to 2.1.3 MRB regarding the Fearless
rule). While they get the benefits of the fearless rule they also get penalty of the blood rage. if they lose an engagement - which isn't unlikely - they lose their transports and become foot infantry.  Remember this only effects the marine infantry units nothing else.
Could this work? I see it as reasonably fair to both sides.
Obviously it will need to be tested and I think vassal might be a good option if anyone would like to trial it with me???
I may also tone down the 2+ CC for 3+ - they're not eldar banshees they're still only psychologically suped-up marines so I think I'd prefer to boost their abilities with resolution rules instead - if at all...