I only use DAZ Studio, so I can't really comment on how the mil4 kid works in poser. But I don't think that DAZ are trying to move away from its poser customer base. I know some people have said they have had problems with the M4K in poser but a lot of others have said they have had no problem.
Personally I prefer this to the M3 kids. I think some of the morphs on sale are really good and  am sure that there will be more that are better and better.