One big one is the fact that you have Tier 3 pirates (along with other ships of equal or higher tiers) flying around in low-level sectors, and other Tier 2-4 ships flying in Tier 4+ sectors. I propose that sectors do not limit your travels to other sectors because of Tier, but instead simply warn the wandering pilot that they are entering a high-rank sector. This will make so many more ships (namely a handful of premium ships like pirates) much more useful in other sectors, and not quite as inhibiting as they are now.
***EDIT***
Instead of having everyone in every sector right off the bat, players should have to reach tier 3 before the restriction is lifted, so they have general game experience.
So when a pilot reaches tier 3, all rank restrictions are cut, and they can use any tier (1-5) ships in any sector.
With the solution you propose, people will not heed the warnings, will go in anyway, will get blown up in their t1 ships, and then complain that Biomorphs are OP
I think the worst part is it doesn’t matter what the enemy rank is, they can all be loaded with T4 guns and missiles. So while we may be able to kill them in our low rank ship, they murder us if we get shot at.