Charlie Papazian get's a steady 87 percent with the Corona that he's been since the 70's...He's happy with it.
He feels he doesn't NEED anything else...like a Barley CHrusher or Malt Mill that people always seem to feel the need to peddle when someone asks about a Corona...Lots of people on here use them...
This is from the Aussie Craftbrewer Site;
Corona mills have gotten a lot of bad press over the years, with claims that they are unsuitable for brewing as the give a very poor crush (i.e. tear the grains rather than squeezing them) leading to flavour and extraction problems. The claims have usually originated from either the manufacturers or owners of the more modern roller mills.
But before roller mills (such as the PhilMill, Valley mill and MaltMill) were available for small-scale brewer, Corona mills were the only ones available. Many brewing books had sections on using and adjusting a Corona type mill. Dave Miller's book from the late 80's had a whole chapter devoted to using and adjusting a Corona mill, and he is often quoted as obtaining extremely high extraction rates from the grain.
There's some info and links here in my thread for tweaking them in my thread.
https://www.homebrewtalk.com/f51/my-ugly-junk-corona-mill-station-90849/
I figure at on average 25-40 bucks for a corona as opposed to the others, means 100 more bucks for other toys or two 50 pound bags of 2-row...
And if it's good enough for Charlie.
And although I'm pretty happy with my Corona, I've been following this thread for it's sheer DIY ingenuity.....
https://www.homebrewtalk.com/f11/using-pasta-maker-mill-grain-75784/
Especially if a 20 dollar pasta machine can make a mill that looks, and acts just like one of the more expensive roller mills....
There's many flavors of mills, no one is better than the other, they all have plusses and minuses with them...as you can see with tweaking you can get high efficiencies with a Corona mill, just as high as with the barley crusher or any other mill...They all have the potential to make great beer, or make pond water, depending on the brewer.....
At my friends using his corded drill (rather than my cheap cordless) I burned through 14 pounds of grain with a great crush in about 5 minutes on my little corona...So with a good drill speeds not an issue...I have also ground an entire grain bill buy hand and it really was no big deal either...
You have to ultimately decide...on how much tweaking or how much money you want to spend on it, but if anyone says that one mill is BETTER than the other, they are FOS....