I still think that modern small-scale flows in the Gullies of mars are gas-lubricated. I don't think I can sustain the giant flood CO2 hypothesis, but it shouldn't be totally discarded, there may still be some value in the ideas.

I'm generally gratified that the last few years of Mars data have swung the pendulum away from a slushy wet blue Mars to a frozen white one. The ESA mineralogical work, building on Phil Chrstensen's Themis work is a major calibration point in the dryness of Mars for the past 4 Ga.

I also think that the ephemeral impact-pumped atmosphere model of early Mars is better than a steady-state but declining atmosphere model. This needs more work and more data.

Time will tell...