I would rather do it with giving mediums more slots, especially at lower tiers. It would allow for higher HP ceiling, but also would allow more versatility and customization beyond just HP-tanking.
Assaults should have 8 module slots at prototype (most logis have at least 8). I would also like to make progression more linear, only 1 module slot gain per tier; this mean standard would have 6 module slots instead of just 3-4, and advanced would have 7 module slots. So 6 modules STD, 7 ADV, 8 PRO.
I would also have logis share the exact racially consistent slot layouts and slot counts as assaults. There should not be a logi with 9 module slots, it gives it a higher HP ceiling than assaults; remove the 9th module slot from the Cal logi, and give it a 4th equipment slot at proto just like the Gallente and Minmatar one. The Caldari one is probably the worst logi at standard tier, it really should start with 3 equipment instead of 2; it has no advantages over other logis at standard tier to justify it only starting with 2. Also, we tend to think of logis as OP, but most logis have pathetically bad at standard tier.
All Amarr medium suits have less module slots than their other racial counterparts of the same tier. Sure they get more base HP, but that's already payed for by being the slowest among the suit type. Amarr lights and heavies don't have to give up slots compared to their racial counterparts, and neither should the mediums.
Assaults and logis are covered, but I would also like to do something about the bacic mediums. Basic mediums should be generalized middle-ground between the assault & logi, it would make the assault truly specialized by comparison instead of the assault just being basic frames with bonuses added. It would also give players the ability to test-drive both assault & logi roles before specializing; right now you can test out the assault role with a basic medium, but can't test a logi role with their parent basic frame. Current set up is bad for testing roles. Furthermore, right now the basic frames don't really have a reason to exist or use once you unlock their copy-cat specialization. To fix this, they should have exactly 1 less module slot than assaults/logis, but gain a second equipment slot; this would make them a truly generalized middle ground capable of test driving both assault and logi roles for undecided newbs, and makes the assaults specialized and distinct by comparison.
In the end we end up with something like this:
Assault & logi STD (high/low)Am: 2/4
Ga: 2/4
Ca: 4/2 (+1 equip for logi)
Min: 3/3
Assault & logi ADV
Am: 2/5
Ga: 3/4
Ca: 5/2
Min: 4/3
Assault & logi PRO
Am: 3/5
Ga: 3/5
Ca: 5/3 (+1 equip for logi)
Min: 4/4
Basic medium MLT (high/low/equip)Am: 2/2/2
Ga: 1/3/2
Ca: 3/1/2
Min: 2/1/2
Basic medium STD
Am: 2/3/2
Ga: 2/3/2
Ca: 3/2/2
Min: 3/2/2
Basic medium ADV
Am: 2/4/2
Ga: 2/4/2
Ca: 4/2/2
Min: 3/3/2
Basic medium PRO
Am: 3/4/2
Ga: 2/5/2
Ca: 5/2/2
Min: 4/3/2
Much more detailed explanation
here