Hi coolmonk,
Yes there are quite a number of mattresses that are a latex/innerspring hybrid (with latex as most or all of the comfort layers). A few examples includes one of the members of this site Baybed and Mattress (which uses a component design where you can choose the individual components and latex layers) and another manufacturer that is mentioned fairly often as well called Berkeley Ergonomics but there are many others as well. The heaviness of the latex would pre-compress the springs slightly more than a lighter foam but this would have no negative effect on the durability of the mattress. A forum search on innerspring/latex hybrid (you can just click this) will bring up a few more examples as well.
Almost all innersprings have some type of foam in the comfort layers (either polyfoam, latex foam, or memory foam) although you can also find some mattresses that only use natural or synthetic fibers and no foam at all. These tend to require more specialized construction methods (such as tufting) to prevent the fibers from compressing and shifting and can be very costly compared fo mattresses that use foam. One lower cost example that uses wool, cotton, and innersprings and is good value is made by My Green mattress that is also one of the members here but it’s unusual to find this type of mattress in this price range.
You can see a few more examples of innerspring / natural fiber mattresses in post #4 here. Some of these are hand built ultra premium mattresses and cost upwards of $50,000.
Phoenix