I don't know how this would work or even if it would solve anything but maybe the suggestion will spark a thought somehow.

Maybe the pool could be split in some way. Maybe make a second pool and migrate miners over to the new pool to even them out. [Tycho] would be running two pools but somehow it would be transparent to the miners

Example, and please don't associate my numbers with accuracy or fairness, create a second pool server and for every 2 > 1GH/s miners allow 4 < 900 MH/s  miners to work in the same pool. Another way to look at it is to group 1-5 big time hashers with 8-10 smaller hashers and separate these groups on different servers.

This is only meant to help the thinking process.

Cheers.