I think the debate about mechanical broadheads will go on forever. A couple of things to consider. If your bow generates a minimum of 60lbs of kinetic energy, then a good mechanical could be a choice. but what distance are you going to shoot? If you are shootin at 35,40 yds. or even farther unless you still have around 60lbs. of energy, that is where you run into trouble.
I keep all my shots at 25yds. or less. I know my bow is generating about 70lbs. of energy....so a good mechanical will work. Last year I was shooting a Browning Bow.....slower, but Quiet .I think the energy was close to 58lbs. so I was pushing the envelope with mechanicals...but I wanted to try one anyways. it was an inexpensive Satellite 3 blade. I took a Button Buck(that I thought was a doe) at 7yds.
The broadhead blasted through at a quartering away angle . it came out through the front leg at the top section were it meets the shoulder. Left a large hole. The deer didn't go 20 yds. The arrow kept going!
if that shot had been any farther away I wouldn't have taken it. I doubt the broadhead would have had the energy to do that kind of damage.
Fast forward to today. 2011 Exile 285fps/70lbs. kenetic energy...swacker 100 grain broadhead....do I think it will kill just about any deer at 20yds.....you better believe it!!
I think if you do your homework, and your bow generates enough energy, mechanicals can work very well.
I have used fixed blades all of my life...successfully. Last year I tried a mechanical.This year "SWHACKER"