Actually, for many things, a balsa core is much better than foam. Balsa has better adhesion, tensile and compressive strength than most of the foams used as core materials. Its main drawback is that if the core's integrity is violated, usually by improper installation of hardware, the balsa core can get wet and rot--leading to delamination. Also, balsa does not allow large areas to delaminate as easily as foam core materials do, since water can wick along the boundary between the foam and the laminate skins, since it can have poor skin adhesion problems, especially with polyester/vinylester resin-based laminates. This is because the foam core materials do not wet out and absorb the resins as well as end-grain balsa does.
As for epoxy based laminates--yes, they're often worth it and often used in cutting edge racing boats, due to epoxy's greater tensile strength. However, epoxy does have some drawbacks, when compared to polyester/vinylester resins.
The biggest one is that most epoxy resins are prone to thermal deformation at much lower temperatures than are polyester/vinlyester resins. This is one reason most of the high-end epoxy resin boats are white in color. If painted dark colors, they can heat up to the point where the epoxy resin can soften and start to deform.
Epoxy resins are often used in repairs for another reason. Epoxy resins have much stronger secondary--adhesive--bonding characteristics than do polyester/vinylester resins. This means that the repairs made with epoxy resin are often far stronger than similar repairs made with polyester/vinylester resins.
I have been going through some reading and seeing the pros and cons of various types. For instance, a balsa core rarely seems better (in my reading so far) to a foam one.
So I am going through the boat porn (Cruising World). Hanse mentions it has 37/43/47/54/63 footers available. Interestingly it highlights that the 37 and 43 have epoxy options. Elsewhere, I have read that epoxy is 'better' but haven't seen the exact reasons versus a typical boat from a more mass market builder.
So, you are buying a new boat, what is epoxy worth to you vs the base boat? Would a 49 foot non epoxy at 650k make you want to step up to a 750k epoxy version in the same size (or switch from one builder to the next from the non to epoxy version). For instance, I have seen a more mass market maker in the above scenario on the low side vs a more custom route at the higher end (both very similar in general design; biggest difference is epoxy vs fiberglass).