HI Annette,
Welcome to the Mattress Forum! 
The EcoSleep mattress from Arizona Premium uses good quality and durable materials. The innerspring unit is the pocketed spring Caliber Edge from Leggett and Platt, using their Bolsa spring and thicker gauge steel along the edges for extra reinforcement in that area. Placed on top of that is 3" of Talalay latex. You may choose the Talalay in multiple ILDs – 19 (plush), 28 (Medium), 32 (Firm), 36 (Extra Firm) – to accommodate your comfort preference. Hopefully you’ll be able to sample these when you visit them in person.
While all of the layers of a mattress work together and contribute to comfort, in this scenario the innerspring unit would be primarily responsible for deep support and alignment, while the Talalay latex layer would primarily be responsible for surface comfort. You can read more about the two functions of a mattress, support and comfort, in this article.
There’s certainly nothing wrong with using an innerspring unit for a support core within a mattress, and many people have an affinity for that type of product and the support/comfort characteristics it provides.
Latex is one of the oldest foams in the industry, the genesis resulting from the vulcanization process invented in 1839 by Charles Goodyear. Foamed rubber (latex foam) began production in 1929 by Dunlop, and has advanced since then. The Talalay latex process became commercially viable in the late 1940s. In contrast, polyurethane foam using the common TDI isocyanate process began production in the 1950s, and memory foam originated from the Ames research project in NASA in the 1960s, and after this discovery was released to the public domain in the 1980s it began to appear in mattresses in the early 1990s. So latex is actually a very proven material, and I think your husband may be confusing it with memory foam, which is the “new kid on the block”, relatively speaking, but it’s still been around for quite some time. All foams are constantly going through improvements in chemistry and production.
Latex is generally considered to be the most durable of the three major foam types, and can be a very durable support core (if used instead of a spring unit). Post #28 has much more detailed information about latex versus springs.
Phoenix