Variable rate springs are great they ride real nice usually softer than stock for the first 1" TO 1-1/2"of travel then stiffen 20 to 25% more than OEM under load. I installed some Eibach springs in a old Ford and they really changed the ride bigtime for the better.
Variable rate is my first choice for a car like this.
You are looking for a good ride, not race track handling.
The theory is that they offer soft springing for normal driving, then quickly compress into the harder springing section when aggressively turning the car.
i have mixed feeling about these, sometimes they're better, sometimes they're not. for hard driving they can upset transitions and mid corner. for normal driving i'd try and stick to the stock rates or just go for it and see
IMO a stiffer sway bar would be better for cornering than using progressive spring. A uniform spring rate is more comfortable than having the rate changes at different points of a bump. After market lowering springs use progressive rate because there aren't room to travel for the same soft and comfortable spring rate, and is a better compromise than a uniform firmer spring.
I just want the correct ride height restored.
The car rides great,and I usually don't carry cargo or passengers.
I just want the best ride for the money that I can get.
For a little compact doing autocross I can see the argument against. For a full size 70s Buick (I'm assuming daily driven) variable rate springs seem like just the right thing. It's not like you'll be launching it into corners at highway speeds, you want a comfortable ride that doesnt bottom out when you do corner a little too hard, am I correct? Buy them.