I always thought a combination of ffxi and ffxiv systems would work great. Have your rank dictate your base stats for example at rank 10 every MRD will have the exact same base stats with slight variations due to race. So basically your rank give auto-allocated stats.Then have you physical level allow you some bonus points to allocate to your character as you see fit. Say 1 bonus point per every 2 levels.

This would enable those at the highest level to still feel a slight benefit at all stages while also allowing for slight individuality, without leading to situations like inviting THM with full str/dex set ups. Also with most of the stats auto-allocated it should allow them to balance the system rather well. If not they can limit the bonus points to less than 1 per 2 levels until it works.