I remember Graham Scollick of CGS showing me the old David Grieve busts of the Waterloo Generals that he had. One had been cast in Metal the other Resin and even in a comparatively uncomplicated object the difference was plain to see.
There are so many advantages to resin that it is easy to see why the market has gone in that direction,
1) Cheaper to post
2) Finer detail and the ability to create more dramatic poses-especially horses.....which have been known to collapse on occasions in metal....LOL
3) No metal deterioration, which I have experienced with Borin, Grieve, PM in the past.
4) Ability to produce in larger scales, which although they can be heavy are much lighter than Metal in the same scale
5) Easier to hold the subject being painted.
6) No need to prime if you are so inclined.
7) Cabinet shelves don't collapse under the sheer weight of metal.
A couple of disadvantages,
1) Coping with resin dust on clean up (although some of the superb casing coming on line makes this almost redundant)
2) The joy of holding a completed model in your hand which has weight and implied value (Just a personal view)
Keith
Resin is a lesser medium to me compared with metal. The argument that you get better details with resin is a fallacy.