Hi EW73,
you're right. I don't know the 747CL, but as far as I know the 747-400 has a 1 PACK ON / 2 PACKS OFF TO ... though the conf. may change from plane to plane.
I don't know what all this 'pressure-bump' is about, it was never a problem, worked just fine, and was ultra-reliable...
No doubt about it. I was talking about the "pressure surge" that might happen upon the selection of 2 or 3 packs at the same time; this thing has all to deal with comfort and is not supposed to be a problem for a large cabin like that of the 747. The less the cabin size, the faster it gets pressurized. Don't want to keep runnin' off-topic ...
Best Regards,
fredgrav