Well, I have an opinion on the M9 bayonet. I am Sergeant in the 3rd Inf Div.
The M9 is a valuable tool, provided it is attached to the rifle. Otherwise, it is not to wonderful, and I prefer my standard combat knife. The blade is to thick to really cut and sharpen effectively, and the little saw teeth on the spine don't really accopmlish anything. Also, most M9 bayonets that I have seen are not maintained very well, being about as sharp as the average MRE spoon. The sheath for the bayonet is very sturdy, but provides only one real way of attaching the weapon to your kit, and is pretty unwieldy. It tends to flop around a lot.
Again, at the end of a rifle, the M9 is a valuable CQC weapon, IMHO. With the full weight and power of your body behind it, you can wreak serious havoc on some badguys. However, as my first sergeant, now Sergeant Major Huffman put it, "When you hear fix bayonets, that's when you know that your sh*t is weak."
Sgt. Kent Newland