This is a great thread and touches on things that are never mentioned in setup guides. I tried this method a few years ago and discovered a few problems that makes it hard to translate to real world. But it does have merit as a good starting point if your starting from absolute scratch. Here's my observations on spring matching w/o shock oil as a baseline setup.

Here's what I noticed: When you initially setup using just springs with no oil to find a matching natural frequency (NR) for the front and rear. After dialing in the correct shock oil, you end up having to play with the springs rates again anyway. You start out usually with a lighter spring rate in front vs rear so it's balanced with no shock oil. But end up with equal or heavier spring rate in the front after getting everything balanced with shock oil. If you take the oil out of your final setup and check the natural frequencies, you usually end up with the front NR much higher than the rear NR. My guess, and this is only a guess, is that a springs NR changes once you add friction. (ie dampening) Also, checking NR on the bench has nothing to do once the vehicle is in motion and weight transfer is added to the mix. especially front to rear weight transfer.

I do think someone who knows more about physics than I do can figure out an optimal spring rate (NF) front to rear taking into account weight distribution. This calculation has to take into account f/r weight distribution. Even though this method does work, I just don't think the result would be a balanced NF front to rear, I think it will tend to be a higher NF in front when compared to the rear. The problem is how do you do the calculations. In the end, I'm back to trial and error.

This does seem to work better on 4wd vehicles, and I'm thinking this is because the weight distribution is closer to 50f/50r when compared to a 2wd. I have an 8th scale buggy with close to 50/50 weight and have used this method of balancing spring NF with really good results. When I do use this method I noticed, I ended up with the same pistons and oil front/rear. The chassis tends to stay level when I hit bumps instead of having that porpoise/front end to rear end bounce. Setting up this way worked well for me on very rutted rough tracks, where corner speed was not the most important factor. Using this method on a smoother track ended up getting me slower lap times. The front end was just too soft.

This method did not work for me at all with a 2wd buggy. You end up with really light front springs in comparision to rear springs. Even with thicker front shock oil, you end up with a buggy that pushes entering the corner, and sometimes oversteers exiting.

The 2wd buggy really does soak up the bumps as long at you go straight. But when you turn and the weight transfers forward to the front springs, the springs are too soft and the buggy just dumps while entering the corner, and the rear end lifts and then spins out when you run out suspension travel in the front. Yes you can compensate for that by maybe playing with shock limiters, oil ect. But you end up with a car that doesn't land off jumps well because there's no downtravel, or the front is too stiff because you will need really thick oil to prevent the front from dumping.

That's my .02

If someone can figure out the math, I believe this method will work. I just don't think the f/r NF should be the same. At least from my experience.