Should i get a normal yorkie puppy or miniature/teacup puppy?

Hey guys I was wondering should I get a yorkshire miniature puppy or a normal puppy. I have studied it quite alot on the internet and noticed that they were unhealty. Is this with all miniatures or just some because I see aload of adds on the internet and see the pictures of them and they dont look unhealthy but that might just be the photography. I know that yorkies have to be in the 4-7 pound range for them to be classed as normal weight and not miniature. if I got say a 4.5 or a 5 pound yorkie, would they still have health problems like bones not being fused and hypoglycemic and other health issues or would they still have some. Also is this just a trick to make people not get miniature yorkies (like little minor dizeases that every dog gets) or are they serious and could make the dog have an unhealthy cruel life. And one last thing , what would the 2 adult yorkshire terriors weight be if i were to want a 4.5-5.5 pound yorkie. Like the yorkie would stay 4.5-5.5 pounds all his life.