I use them. As far as durability goes they are darn near bombproof. I missed a javelina in Arizona last year and the silver flame tipped arrow skittered across the rocks. I just had to touch up the nicks a bit and it was good as new. Arrow flight is great. I see no difference between my field tips and the broadheads.
Fortunately for me cost is not an issue at this point in my life, something for which I am truly grateful and thankful for, so I don't have an issue with forking out the dollars for this broadhead as in my opinion it is one of the best out there. According to Dr. Ashby it is the best broadhead in it's class.
And sharpness...All I can say is use a broadhead wrench to put them on, don't use your finger as a draw check, and watch your thumb when you pull these from your broadhead target. I have no problem shooting these repeatedly into a broadhead target and they stay as sharp as they were when I got them. I've been working on some Grizzly 160's to get them sharp enough to hunt and I just can't get them done right; These Silver Flames don't need that kind of work. So for a two blade, rated best in class by Ashby, durable, sharp, well made, accurate, flies like my field tips, broadhead these are an excellant choice. If you don't mind the cost and can afford $20+ dollars a head. I'm taking them to Africa with me in August and my wife will be shooting them out of her mechanical contraption as well.
I know I'm going on a bit here...but if you do manage to damage a blade enough that it won't work anymore you can can get a replacement blade kit. Also they come in five different sizes from 100 grain to 210 grain. You can get a test kit of 125, 150, and 180 grain heads. I'm shooting the 210's on a Beman MFX classic with 100 grain brass insert and 3 grain per inch weight tube. With my arrow length at about 27 3/4 I have a 700 grain arrow.