I haven’t read the articles you mention, and I’ll certainly look out for them, esp. the thiolins, Thanks. I think you have a very good point. Certainly it is hard to see how nascent pre-life could survive on Mars, either rapidly exhausting its resources or withering under the radiation. The speed of evolution is a problem in any model. All tend to assume “world enough and time” but as you point out, on Earth it had to have been relatively fast. I agree that once the transition is made, anything that preceded it would be wiped out. But I’m not convinced that robust intermediate pre-life forms could not exist elsewhere over long time periods; they may not be that fragile. The system could continue indefinitely if it acquired a set of reactions to reliably regenerate the initial conditions:
(C,H,N,O,P, S, Cl, Metal ions )-->[XX] --> (C,H,N,O,P, S, Cl, Metal ions ) -->[XX], etc…
The competition for resources would push the system to increased efficiency, this would result in positive feedback, accelerating the race to even greater efficiency until something recognisably alive turns up and wipes everything else out. In a resource depleted environment the transition to life would probably fail, the system collapse back to a less efficient model that would start the cycle over again, possibly for ever. In an over-supplied environment, the selection pressures might be small, and the pressure to evolve to something more complex less intense. I suspect that there are planets where this goes on; but I wouldn't bet on it being any where close, or seeing it any time soon.

Andrew