In a nutshell:

Due to the CPU/PG, shield suits are better off fitting armor plates than regulators

Due to how low the delays are anyways, there is no point for the most part, and it's better to just get more HP

Meow

Well, the delays aren't that low on the minmatar suits (not compared to the Caldari at least)... but minmatar suits has much better uses for its low slots, just for the sake of getting more bang for their buck than using a shield regulator.

I fit 1 complex regulator on all my winmatar fits, I like me shield regen.

And 1 energizer as well.

Logi I put 2 plates, 1 shield reg, 1 armour repair, 1 shield energizer and 3 shields.

Assault I put 4 shields, 1 energizer, 1 shield reg and 1 complex reactive.

Heavy I put 2 shields, 1 energizer, 1 complex reactive and 1 shield reg.

And with the passive, that's 45% per complex shield reg before delay is added.

I tried running two shield regs on my logi and it us nice but its far too squishy.

So... in effect, you are still using armour on all those fits, you are just picking the regulator over something else.
(My winmatar logi runs a kin cat instead of the shield regulator, but I can only fit 2 extenders in the highs... talk about squishy )

I am sure many of us Minmatar and Caldari suit users were excited to hear the news of shield modules being buffed... Personally I found the extender and recharger/energizer buffs to be quite reasonable. Not perfect necessarily, but good.

However, the shield regulator is still the odd one out. Even with the minor buff they received, I find it difficult to justify using them.
At the same PG but less than quarter of the CPU I can fit a basic plate (at almost a hundred HP) instead of a shield regulator that shaves off a whopping 35% off of the shield recharge delay. Frankly, when you also consider how low any shield tanked suit runs on CPU, losing out on that much HP for a an extra second or so off shield recharge just doesn't seem like a sensible trade off to me. And thus, I will continue to be one of those dual tanking scum.

So, basically, it looks to me that brick tanking still is the optimal choice :(

Any thoughts? I know some people out there must use regulators, tell me why they are worth it in your opinion.

True, but the delays are still quite low.
Not as low, but still low.

Though I believe Minmatar suits should have lower delays than Caldari and have higher base regen speed.

minmatar have never been known for amazing shield or armor tanks... speed and size is their tank. perhaps we could reduce their hitbox sizes?

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%.

Nah, they have been known for speed and EVERYTHING.
They use armor, shields, even hull sometimes, and their tank is not too shabby either.

A regulator basically needs to knock delay down to 1-2s and depleted delay down to about 2-3s for it to be worth loosing out on 65 extra HP AND 2 passive armor reps. Since it's not likely that it'll ever happen, I'm afraid regulators aren't ever going to be useful enough to use for my Winmatar assault.

Its is very important that regulators are preferable to armor modules to a shield tanker, otherwise shield tankers will dual tank; which is bad because it nullifies the importance of weapon damage profiles since a dual tanker has no weaknesses to any particular weapon damage profile.