chlorox Um. The chassis of the Evo (and the Vesuvius from which it comes) is extraordinarily strong; I don’t know if it costs more or less than that of the Vostok, but I don’t think it’s inferior to it in mechanical terms.
It could make sense to not offer the Evo if that resulted in any saving to ACS, but since they will keep producing the Vesuvius… (and the Minima, and the single- and multi-group Vostok), what benefit would they derive from not offering a slightly smaller machine with a different look, but requiring the same components and zero additional costs? Personally, if they both had been available a year ago, I would have gone with the Vostok, but there are people for whom the larger footprint (and the ‘outré’ looks) are no-go.