>If the mission is to collect or mine asteroids, that would change everything. All the above assumes some other purpose -- for example, Mars surface mining.
If we had the ability to mine mars, that would change everything. But this is precisely why I'm suggesting that a station in space might be superiour to any mars base. A station doesn't have to be near mars, lots of locations, asteroids and points of interest are closer to us than the surface of mars. Even going to mars will be easier if you have the station first.
>there's no justification to use orbital solar with the attendant high capital costs and conversion losses
Are you talking about orbital solar for a non-existent mars base? A space station can have 100% uptime of their solars cells without the problems dust brings. Mars is the one with conversion losses if they need to store any power for any length of time.
>being able to live below the surface in any of the existing lava tubes as protection
Radiation protection is just a cost figure for a station. Converting lava tubes into something we could use seems like a herculean effort without even knowing any safety aspects. You're just limiting your own space on a dead planet.
>artificial gravity
We could spin the habitat. It would be easier than testing lava tube methods of engineering.
>Remember that Mars surface temperatures regularly drop to -100F overnight. Temperature extremes would also be an issue in a lava tube, but with less severity if the site were carefully chosen.
Stations win again as we've already solved this.