"The solar flux on a given area of the Earth is pretty impressive, too, but it's a long way from actually being able to utilize it effectively."

I don't understand what you are saying.

"And while space power satellites have a more reliable and stronger solar input, there are also losses involved in transmission and conversion."

This is true.
Also problem with SPS is maintenance. And to get light weight panels, you will pay in their lack of efficiency as compared to types of solar panels you could use on earth [or solar power collectors- such using solar reflectors and heating salt].
But getting back to "losses involved in transmission and conversion", if SPS are used to make rocket fuel in Space [something I'm strongly in favor of] then "transmission and conversion" are less of a problem [though of course, making rocket fuel is a conversion of energy].

I think though that in the context of thinking of some way to create power in space and beaming it to Earth's surface, niche markets such as the electrical power needs of the military, makes some sense. If the military does actually spend about $1 per kilowatt hour and can be expected to in the future to have such needs, this makes more cents than trying to sell electrical power to a general market that currently pays about 1 penny or less per kilowatt hr.