Muzzy -
They make it easy to tune your bow. The way I look at it, your poor broadhead flight is an indication of the bow tuning more than that of the broadhead tuning. Muzzy is as good as about any out there for tuning.
They are durable, VERY DURABLE! I have never had one fail. I am sure someone somewhere has but not me.
You can use them over and over. I bought some 100 grain 3 blade many years ago and have not bought a new broadhead since.
You do not have to sharpen the blades. They are sharp out of the package. If you shoot an animal or damage a blade somehow, just buy some replacement blades and throw away the old blades (or better yet, save them for practice blades).
They have practice blades available or you can do like I do and use your old used or damaged blades for practice. I have several extra if anybody needs them (100g 3 blade).
Why would I try anything else? If it ain't broke, don't fix it. Like Muddy said, "they work for me, PERIOD". If I had trid Thunderheads or some other high quality head first, I am sure I might be saying the same about them too.
And, like LIVE4RUT said, "they always zip right through them". What more do you want? That is all I am after.