A couple of months ago I ordered a Sundia Sun, and it quickly became one of my favorites. It came with the heavy metal washers, and this lightweight axle;

(Picture shamelessly swiped from a post Scharling made here in 2013)
Recently I ordered a couple more Suns, but they both came with plastic washers and the heavy steel wide fixed axle. They weigh about the same as my first Sun, but even a beginner like me can tell the difference in how they play.
I really love the axle in my original Sun. (the ones in the picture) So, are these axles available anymore? I'd love to find a few of them.
Am I just better off spending a bunch of money converting everything to the black teflon coated aluminum axles instead?
Has anyone here played the aluminum ones?