I suspect you could probably work with pretty heavy leather, since the 3mm cardboard it's designed for is going to be pretty comparable to 5-6oz.The bed size might be too small for typical panel sizes though.
That thing would be useful for cutting leather to a pattern. Jigsaws just move the leather up and down, leather is too flexible for routers, scissors don't work well on thick materials, and knife work takes a lot of skill.
