I upgraded from a MK2 1.8 limited edition jasper conran and the Mazda was extremely reliable and the handling was beautiful, direct and excellent fun but found it somewhat lacking in power BUT on thither hand the Z has bag loads or power , also puts a smile our face . I admit running costs are marginally higher but these are two different cars with different value paradigm's.
I have not found the costs t high (albeit this is subjective) , but comparatively there is no contest you want more power, more involved driving experience.
Hope this helps