I thought I read the Warriors had MIM MSH's. I will have to take a look. I was thinking of adding a Kimber magwell/MSH combo, but I decided to wait to get the gun first and see how I like it before I drop the cash.
I've accidentally managed to replace the MSH on two of my favorite 1911's - a Para Tac-Four and a Kimber Compact Custom - with steel.
Definite increase in weight, but they both use an "Officer's" length MSH, so it's not too terrible.
I was in the plastics business for more than 30 years at the former day job. There are "engineering" plastics out there that shame steels in many applications, and this is one where it probably doesn't matter at all except for the weight.
I've been having problems with the Para breaking MSH retaining pins (I think putting a real Para pin in it - no idea who's pin broke the first time - fixed that) where the metal replacement housing's inability to flex may have contributed. Go figure....
S & A makes an aluminum MSH as well which is probably lighter that the steel one. I want to put one on my Kimber compact Alum/steel. I called about 2 months ago and they were out of stock, but glad you reminded me.