I have a 5" government model and a 3.5" officers model that I carry quite a bit. I've carried a 1911 more than any other pistol I have owned ever since I first got my permit back in '92.
I have always used a leather IWB holster and if you get the right holster IWB or OWB and good gun belt the weight is not really noticeable at least in my experience.
As far as leather or Kydex goes, get what you like. My preference is leather, as I carry all my pistols in leather, I just have never cared as much for Kydex but I know people who swear by them, it's all about what you like and are comfortable wearing. Both Kydex and leather have pluses and minuses and as others have said, dont skimp on the belt as it is as important as the holster. The best holster in the world isn't going to be all it can be with a belt that sags and won't support the weight of the pistol your trying to carry in it.
Just my opinion, take it for what it is, lol