Interesting, I fiddled around with a corona mill for about a year when I first started brewing and never could get a consistent crush without either having a ton of flour, or a ton of uncrushed grain.
I then switched to a barley crusher 2 roller which I've used ever since. I condition my grain 3%, crush to .033" and get pretty awesome consistency. I've run at least 2-3,000 pounds through that mill and it's still doing great. I pull it apart to run a wire brush between the knurling and lubricate the bearings about every 200 lbs or so.
I do plan on upgrading to a 3 roller at some point soon, but will praise the two roller I'm using endlessly. It has really been a hell of a trooper. All I remember about the Corona mill is it was a pain in the ass lol, I really just feel if it's between spending 40-50 for a corona mill or 100 on a roller, the roller would win my opinion every time.