Here we go again, talking at cross purposes !

Without wanting to pick a fight, please read the following then take a deep breath and count to ten before hitting the reply button.

1) Yes, the Sabbatier process is simple, but it needs pressure vessels and thermal processing. This is simple on Earth, with human control but needs purpose-built equipment. I am fully aware of Zubrin's demonstration of a pilot-scale plant for doing this, and the concept of scaleability, but this still adds complexity to the mission compared to the simple but mass-expensive method of carrying your own propellant.

The saving grace, as I see it, for in-situ propellant production is that you would need something pretty neat to give 2-year's storage of cryogenic fuels if you took your own. An in-situ plant could cope with leakage by constantly topping-up. (or you accept the lower ISP but huge storeability of solid propellants for the return journey, and cut complexity and risk at the cost of a modest mass penalty)

2) The landing requirements in terms of positional accuracy may well be comparable to Apollo, but the landing DIFFICULTY is not. Apollo had no atmospheric variation to deal with and a gravity well substantially smaller. We have seen of late the issues relating to altitude of parachute deployment and cross-winds that affect target accuracy on Mars. These are non-trivial and the only sure solution is extra fuel for the descent to give cross-range capability perhaps also with some sort of lifting body for crude steering during re-entry)

3) You "assumed" that mission duration would be identiacal for a Phobos mission vs a surface mission. I DID NOT, and for good reasons. A 1-month short-stay Phobos mission makes the total mission duration about half of that for a surface stay with return at the next conjunction. In broad terms, mission duration is the main parameter driving cost and risk. time=consumables=mass=cost. Risk of accident is proportional to mission duration (plus you have to add or multiply the risk of special events like orbit insertion and departure, and atmospheric passage). The whole point of doing a "fruitless" Phobos mission is to test everything at about half the cost, risk, and time of a full lander mission. I know the science return is way smaller than half, but that's the way most of the world works.

In any case, as other posters here get excited about, you probably wouldn't want to sit on Phobos for 18 months getting your gonads fried. The risk is moderate, but far from negligible. A surface mission is a little safer from a radiation perspective, although you could dig-in to Phobos in the same way that a surface mission would, but then we go adding mass and mission complexity again.

4) There IS a "church" of Zubrin, IMHO, for good reason. He is a charismatic visionary who preaches an atractive "gospel". I admire his goals, but not all of his methods. I recognise that he has made major contributions to the ideas of Mars programs, but I don't think he is taking the right path between the threats of cost and risk.

Personally, I would rather see either a slower and more careful approach than Mars Direct, or one even more adventurous where a group of, say, four volunteers set off on what was likely to be a one-way mission to Mars, with supplies for 3-4 years and a promise of resupply.

5) I am not and never have been a member of the Mars Society (or the Australian branch). I have never attended a Mars Society meeting. I HAVE attended and enjoyed a Zubrin lecture. I have attended and spoken at Mars Society Australia meetings and offered technical advice to them at times, but I value my independence.

6) Before getting frustrated, let's see why some people count with apples and some with oranges. There is often a reason, so rather than getting cross that you've told us already about your apples, have a think about my oranges...

You may have already discussed this in many different ways, but you haven't approached it from my viewpoint, and probably not from that of others who "won't listen". Think about some alternatives and give them a fair go. You may be surprised at how receptive people are if you can approach them in terms that they understand, rather than trying to force your view on them.