Swayback,
The typical A. micholitziana has smaller, narrower leaves, scalloped as you indicated, and has mottled to reddish petioles, at least in the specimens I have seen. The green on the leaves was not as dark as the green on Frydek, but that could be due to culture and/or the fact that Frydek does not have any pigmentation on the petioles or main veins. There are other species of Alocasia with both green and mottled or colored forms, such as A. brisbanensis and A. macrorrhizos, so lack of color (other than green) would not preclude Frydek from being a sport or variety of A. micholitziana.
As for A. sarian, I see it as highly unlikely to be a cross involving A. micholitziana and A. zebrina, not impossible but I'd be really surprised if it were the case. I've crossed A. sarian with A. odora and did not get any indication in the progeny of A. zebrina in the parentage. The progeny were exactly what I would expect from crossing two species, not from crossing a species and a hybrid together, or two hybrids together. As for A. zebrina, i've crossed it with Borneo Giant and that is about the only way I've been able to get a colossal plant that looks and feels much like A. zebrina, so crossing two smaller plants yielding a giant plant makes little sense to me unless one of the plants has the genetic constitution to be very large, but in recessive genes. This kind of thing could show up in progeny of a selfing, and no doubt would be really notable to the breeder.
I agree wholeheartedly that any breeder that would produce a plant like A. sarian would be certain to want credit for it. A. sarian was described in David Burnett's IAS monograph on Alocasias quite a few years ago, before it was even on the market, and so i suspect it was a wild-collected plant that was spectacular enough to get into the market on its own merits, without "improvement". Believe it or not, i find A. sarian to be difficult to keep alive, although I've seen at least one extremely impressive, large specimen of the plant growing in the yard of a person who is not an Alocasia expert, so go figure!
