Quoted from PanzerFreak:Many of the best games do have plastic ramps but also have metal habitrails coming off of them. Stern has offered metal habitrails as a premium feature in the past with games such as Star Trek premium / LE. It was very unexpected and welcoming to see all versions of MET offer metal ramps and rails.
What's the advantage of metal habitrails? I guess I'm missing something here. Myself I prefer the speed and smoothness of plastic returns but metal is fine as well. Really, not much of a difference at all.
Even from a value perspective. I just looked at all my machines and the two that have the largest number of metal habitrails, JD and TFTC, are the two cheapest machines I own.
I think your other points valid though.