Increasing the variation of the breeds based on nano buffs could be a viable way of making breed choice much more important.
Examples:
Reduce inertia buffs everyone for 120 evades currently. The buff could instead boost opifex by 150, solitus and nanomage by 120, and atrox by 90.
Absorb buffs could buff nanomages by 5% more, atrox and solitus by the current amount, and opifex by 5% less.
Max health buffs would have the highest benefit for atrox, same as current for opifex and solitus, and lower amount for nanomage.
etc etc etc.
While my examples might not be the most suitable the point is that buffs could help seperate the breeds.