As long as axle nut torque is kept within common range there should be no problems. However we see a lot of single speeds and fixies with very poorly done set up/assembly/tightness torques... As to the lack of a chain tensioner remember that the correct tension of a fixed/single speed chain is no tension. having this work out without the ability to change the cog to ring distance will be mere luck, until things wear then there's no ability to remove the wear induces slop. Andy.