When I see a front brake on a fixed gear bike I see it as a smart thing to do.

I hardly ever use my front brake, but when I need it I need it.

As for conversions, I see them as a good use of resources; I wonder if the rider has ever had or will have a pedal strike; and I wonder how much difficulty the rider had with chain length, chain line, chain ring and cog issues.

I have a friend who rides a conversion (to save money) and he had a pedal strike with the original 175mm cranks.

He changed to a 165mm crank and that solved the pedal strike issue.

As for the chain length/line/ring and cog issues, he got some good guidance from our lbs and didn't have much trouble.