I know some people who will not allow flux in their houses and others who would solder nothing without flux.

I have read tutorials about soldering and the use of flux is either encouraged or not.

I have used Tix Flux for years with no apparent problems, on track and electronic items, like decoders.

So I am turning to this group for some reasoned arguments for or against the use of flux.

What has experience taught you and what has your own research taught?

Flux just makes the job go better.  The rosin core solders work, but the flux can dry out, or you just don't have enough flux for the job.

A little flux just makes it work better, and it won't hurt either.