The whole aluminium thing being short lived stems from the early MTB days when mainstream manufacturers were going over to alu' from steel - For the vast majority of users fatigue was/is never an issue - I would really not worry about it. Lots of steel frames crack too...
If you just want a bike to ride then alu' is fine - aesthetics wise though (if it bothers you) a fat tubed alu frame is fine for an MTB but on a street fixie it's a million miles from the lovely classic svelte steel 'look' that most of us crave.
The whole aluminium thing being short lived stems from the early MTB days when mainstream manufacturers were going over to alu' from steel - For the vast majority of users fatigue was/is never an issue - I would really not worry about it. Lots of steel frames crack too...
If you just want a bike to ride then alu' is fine - aesthetics wise though (if it bothers you) a fat tubed alu frame is fine for an MTB but on a street fixie it's a million miles from the lovely classic svelte steel 'look' that most of us crave.