I still think the solution on some shield fits is shield impairment stats. You could tune it with different modules, but pretty much make it so that light weaponry doesn't do much to stop shield regen (on shield based suits). That way shield players can get from place to place a little better than armor players with their HP being restored quickly, but if they lose all their shield or get a big hit all at once then their regen delay starts.
Then you'd also maybe make regulators give a bit of a buff to the impairment rate of shields.
Shield scouts and logistics would have a negligable shield impairment rate while shield assaults would have the best followed by sentinals and then commandos.
Ideally, you'd balance damage around what single rounds of anti-armor weapons could do. Combat rifles hit shield for about 26HP while rail rifles hit shield for 42HP.
So I'd make a shield assault suit start with a base impairment rate of 42HP. This would require you to fit a Duvolle AR with damage specialization to V in order to break it.
Base armor suit (and most logi suit) impairment would be closer to 10-15, requireing a dedicated fit (ideally with lowslot mods) requireing armor HP sacrifices in order to change.
If regulators boosted impairment by the same amout as they decreased shield delay (PRO @ 35% with 10% skill bonus = 38.5%) that would turn this 42HP impairment into 81HP and 98HP impairment for minmatar and caldari PRO max regulator fits with max skills.
The PRO caldari suit would be able to regen through everything except a max skilled viziam scrambler shot, while the minmatar PRO assault could regen through unskilled ADV scramblers or unskilled TAC-ARs (leaving basically scramblers as the main rifles that stop regen, along with shotguns, grenades, PLCs, FGs and MDs, as valid shield stoppers).
Tl;dr: In an ecosystem where the most
light weapon DPS is around the total amount of shield that max extender assaults can carry, giving shield users the ability to "impair" a large chunk of incoming DPS means that AT best they may get 50-100 eHP of buffer during a frontal assault, but also the ability to retreat and counter attack more quickly while still maintaining a concern for their smaller buffer.
Alternatively, impairment (shield delay) could be a function of a % of total shield HP at the time of attack. The bigger your shield buffer, the higher your chance of 'impairing' oncoming damage. So a min suit would continue repping as long as it had 25% of its shield, caldari would be 35% and gal/amarr would be 85 and 90%.