I'm wish there weren't so many threads out there regarding this issue. But in saying that there are so many opinions about it. I personally have had the import springs and had the US springs. Frankly the import springs for me failed in about 4 trips snowwheeling on them. Remeber what I said SNOW WHEELING. NOT ROCK CRAWLING. I don't know why they failed so quickly and had very good customer support getting another set of springs from marlin. They sent me a US made set and like blackdiamond said earlier they failed in a week at Moab. Now the front set was the only one that failed and I still don't understand what happened. I have 2 friends in my club that run the marlin 4" springs as well. One friend has had them on now for a few months with no problems at all. Another friend had the same thing happen to me in just a few weeks. Both sets were the US made springs. I just think that my buddy and I some from a bad batch or something. This is very wierd beacuse no one has had this much problem with the US made stuff from what I've been hearing. I since have gotten a third set of front springs to replace my US made set. Marlin is very good about standing behind his products and I support him mostly because I know that if I had a problem he will take care of it.
If I were use another set of springs I would honestly run a hybrid set fo rears up front. I have a truck setup this way as well and really like it. Now for the rear springs there are so many options. I don't think there really is a clear answer out there to be said. Just do your research and go with what you feel is best for you. If I had to buy from one of the 3 it'd be Marlin hands down.