Like any oil-based neoprene, the production of limestone neoprene is an energy-intensive process. However, Yamamoto, the main producer of limestone neoprene, argues that its production process uses one-tenth of the heat used in refining petroleum. This heat is made from burning used tires and using hydroelectric power sourced from several local dams, and any waste heat is then reused to power a local eel nursery. The fact that Yamamoto's neoprene is considerably warmer due to its high micro-cell structure also means that less neoprene is needed in the production of a wetsuit. In other words, 2mm limestone neoprene is as warm as a typical 3mm sheet of neoprene made from oil, which means there is less neoprene needed and less of an environmental impact.
Because of the durability of limestone neoprene, wetsuits made from it tend to last 2 to 3 times longer than wetsuits made from oil-based neoprene. Lasting suits reducing the 'turnover' rate of wetsuits, which means less wetsuits will end up as landfill if constructed from limestone neoprene, as opposed to oil-based neoprene. In this regard limestone is definitely more sustainable than other neoprene.
So...Yes, limestone neoprene is arguably more eco-friendly than oil based neoprene, but there's a long way to go before neoprene can be truly green!