Back in the summer I started a trial on module verses bare root transplants for leeks see
http://hopesayglebefarm.blogspot.com/2008/06/leek-planting.html
We are now harvesting the resultant crop, the module plants were planted in early june while the bare root transplants were planted mid june. The two trial batches were the same variety and were in adjacent beds.

The untrimmed plants show a difference in the quality of plants, the bare root transplants are on your right as you look at them.

But the trimmed plants show the real difference, again the bare root transplants are on the right. The bare root plants are bigger with significantly longer shanks. Considering these were planted later than the module transplants, the advantage to us of using bare root plants seems obvious.
This doesn't mean that we are abandoning module leeks entirely, I intend to sow some early under lights by early February so they can be planted with the onions so achieving an early crop.