I really dont understand why higher tier harversters were created to start with.
More options to boost your economy.
IIRC, higher harvester tiers were introduced before higher tier econ stations were introduced. As such, these two lines were never compared to each other when their stats were decided upon.
Eh, Well, Aside from slightly altered strengths and weaknesses (Or rather, Stats), Still basically the same thing. Same useage, Same limitations (No wormhole, no repair in combat (Which is still a good idea), painfully slow for anything aside from max-building coverage micro) I really think that they should have something to different them from normal shields, aside from slightly altered stats.
Well, when they were first introduced, they didn't shrink their forcefield radius as they took damage. That certainly gave them extra use, but done strictly (same radius from 100% to 1HP), it turned out to hurt durability.
Maybe if that mechanic is brought back, but with a forcefield radius reduction in size at really low HPs, (like start shrinking at 20%, rather than starting to shrink at the normal 100% - 1HP), that could work and differentiate the two lines.
Also, a mechanic similar to that would be great for Spirecraft forcefield bearers, though with an added minimum radius on top of that.