I think that tier 6 would be a good idea and that it would help with the problem of not having enaoth people playing legendary now there would be two tiers insted of one (like the other clases(recruit and veteran)) This is just a sugestion but maybe they can have 5 modules and be faster insted of slower but not have better modules (like the other tiers) and be only have a little bit more health compared to the other tier diference.
ps: Please leave other sugestions here