Track racing bike-build

From WW

Hmmm... Cartridge bearings of the size used for external BBs are designed for bigger loads than even track sprinters put through them, and the cage would have to disappear completely before the balls could be far enough apart to significantly affect radial clearance. The post you quote goes on to spout some even more tenuous bullshit about rider feedback

if it doesn't flex at all the rider actually can't ride at maximum output as well. This is why some riders prefer to go for less-stiff crankarms (such as Sugino Grand Mighty or SRM track powermeters). More flex doesn't mean lost energy -- it means a rider at the limit can manage the limits of his power input by allowing the cranks to work with him a bit.

The proper answer:
Power lost in flexing your BB spindle and cranks is vanishingly small compared with everything else. Old fashioned cranks are good enough for top riders. External BB cranks are perceptibly stiffer in terms of torque wind up of the axle, crank arm stiffness is another matter and largely independent of BB design. When it comes to solid aluminium cranks, they are all about the same shape, so the heavier ones tend to be stiffer. The limiting issue with cranks is, once again, torsional stiffness, so the only way to improve them is by moving material from the centreline where is does fuck all good to the periphery of the cross section, which is why Shimano Hollowtech cranks always test so well.

The Omniums are cheaper than Campag by the price of the Campag BB, they are stiffer (I've ridden both, and you can feel the difference), albeit that the extra stiffness will make about 0.0001% of fuck all difference to your performance, but also quite a bit heavier, again a matter of almost no consequence on a track bike but it might amount to 0.2% of your total bike+rider weight, which could hold you back by 25cm on the first (250m) lap of a standing start event.