Solid guide rod & one spring vs SA 2pc guild rod & 2

I have only been around for a week or so but I have notice that a lot of XD shooter have replace the Springfield Armory's two piece guild rod and two spring recoil system with a one piece guide rod and single spring.

I understand that the ability to put a stiffer spring then the factory springs in the gun helps reduce felt recoil. But I am left wondering if the one piece guild rod and one spring work fine why did SA go to the effort of making the more complex two piece, two spring recoil system in the first place?

This is just conjecture on my part, but one answer might be the ability to get two different spring rates during the cycling of the action. If one of the springs is less stiff then the other spring then you will have a two stage spring rate. At first the action will be less stiff, until the softer spring bottoms out with coils touching and then when it does you suddenly get a stiffer assembly.

How does this two stage spring rate help the gun cycle? Again conjecture on my part, it could help reduce forces when the action locks up. Since the system is going to get less stiff before the action closes, and the slide will have been slowed down striping a round out of the magazine acceleration will be less right before the action slams shut possible saving wear and tear on the gun. But when the slide is full rearward the system is very stiff (ie high forces) since the soft spring is compress to solid coils thus giving you the force you need to reliably stripping the rounds out of the magazine.

Has Springfield Armory ever commented on the use of one piece guild rods and single springs? Did the original HS2000 have a one or two piece recoil system? I am tempted to try the one piece system to help tame some of the muzzle jump on my XD-40 but at the same time I am leery to change the gun as I am sure there were reasons it was originally made with a two spring, two piece recoil system. Comments, suggestions, and smart @$$ remarks are always welcome.

Thanks
mcb