I have done experiments with Arisaema seeds. I split seed batches of 3 (one tropical, one subtropical, one temperate) species in half, sowed one half straight into my normal sowing medium and one half in ziplocks with moist vermiculite. Once germination started in the ziplocks I transplanted them to the same sowing medium. With all 3 species the vermiculite versions came up a couple of days earlier above soil than the ones sowed straight into the same medium. The ziplocks and sowing pots were all in a kitchen cupboard so temp was the same for both and I transplanted to the same depth as the sowed ones. My guess is air is indeed an important factor, albeit not to such an extend that they germinate weeks earlier. If Arisaema seed is viable at room temp most seedlings will come up within a month after sowing anyway and I could not see any differences in % that came up.
Still I would not advise to sow in vermiculite because transplanting into growing medium poses a risk (breaking the radicle etc....). For this reason I have never understood why the Reno method got so popular, certainly given the fact that the Reno method was developed to see the moment of germination, not as a new sowing technique....