On the heavier hydrocarbon components: methane will burn with a...

On the heavier hydrocarbon components: methane will burn with a yellow flame if the combustion is incomplete (as you would typically get in a flare tip) think about turning the air valve in a bunsen burner at school. When you fully open the valve the flame turns blue and gets a lot hotter, when you close the valve the flame goes yellow. In both cases it is burning essentially pure methane.

The best sign of heavy hydrocarbons is visible smoke and I can't see any of that.

It wouldn't surprise me if the whole thing is pretty complicated, e.g. coal is not a very strong rock it is possible at this depth and stresses that as you reduce the pressure the any fractures and other permeability starts to close pretty quickly so your drawdown goes up in the area around the well the pressure becomes very low and you start desorbing gas, but it is hard to get a big flow rate because the permeability has dropped and therefore the area that is being influenced has also dropped. It may work with highly deviated/horizontal wells but unless they have massively choked back the wells they are testing it is hard to see how a vertical well can be economic.

Without some detailed rate and pressure data it is really just speculation. I seriously doubt STX will make any of that available (nor should they) so the only way I can see to get comfort around what a major development could look like is either long term data (i.e. wait a long time) or resource certification from a reputable firm.