Has any one tried making an FSL antenna using different length ferrite rods?

I am wondering how much the performance would be compromised if a mix of (say) 190mm and 100mm rods were used instead of all 190mm.  What would happen if only every third or fourth rod was the full length?

Using a proportion of shorter rods might be a way of keeping the cost and weight down provided the performance was not diminished too much.