Here's a paper indicating another strike against the likelihood of habitable tide-locked worlds and habitable worlds of low-luminosity stars:
Barnes, R. Mullins, Goldblatt, C., Meadows, V.S.,Kasting, J.F., & Heller, R. "Tidal Venuses: Triggering a Climate Catastrophe via Tidal Heating
. 2013 Mar; 13(3): 225–250
"…we show that terrestrial exoplanets orbiting low-mass stars may be tidally heated at high-enough levels to induce a runaway greenhouse for a long-enough duration for all the hydrogen to escape. Without hydrogen, the planet no longer has water and cannot support life. We call these planets “Tidal Venuses” and the phenomenon a “tidal greenhouse.” Tidal effects also circularize the orbit, which decreases tidal heating. Hence, some planets may form with large eccentricity, with its accompanying large tidal heating, and lose their water, but eventually settle into nearly circular orbits (i.e., with negligible tidal heating) in the habitable zone (HZ)."