I grew up going to Mountain Man Rendezvous with my family. I learned to throw a hawk when I was YOUNG.
To this day, I love hawks. I don't throw them much anymore, but every now and then, I will pick one up and give it a whirl.
Back when I was in highschool, I practiced ALOT with one for close quarters. I would use the hawk by itself, with two hawks, or hawk and knife. With practice, it is a bad arsed weapon. In fact, before I turned 21, it was the weapon that I chose to keep in the Jeep with me (along with an old Ka-bar) to defend myself with.
I prefer the standard hawk. That is, no hammer poll, spike, or pipe bowl. Here's why:
1)Light is fast. Stuff on the back adds weight. Weight adds some striking power, but not enough to justify sacrificing speed.
2)The way I use a hawk for CQ, the poll of the head is used as a bludgeon, and the edge is used for either the coup de grace or for hooking/slicing. A spike backed hawk can't be used for this. It has the same problem that the edge has, that is, it gets stuck in the target. This is bad if your target is still mobile or can hit you back.
3)In my experience, the addition of a hammer poll does not help that much when it comes to hammering. At least it is not worth the extra weight to me.
Now, if I were punching through mail or heavy leather armor, I would choose a spike hawk. Cold Steel's claim of punching through a steel helmet with the spike is probably true, but I will never have the need to do that. If for some unforseen reason I need to take out a sentry with a hawk, (what are the chances?) I can GARRONTEEE that I will not hit him in the helmet with it.
If you decide to get a "traditional" hawk, (HB forge, ect...) or for those of you that have one already, may I make a suggestion? The tapered wood handles are not CQB (or work) friendly. When you sweat, the smooth wood with a gradual taper wants to slide out of your hand. To overcome this, carve a shallow but wide groove all the way around, just below where your little finger would be. The groove should be half the thickness of your cord in depth and twice it's thickness in width.
In this groove, tie a constrictor knot, or some other binding knot (a turk's head knot would look good, but I can't tie one worth a flip) with para-cord or some other line of similar thicknes. Tie it very tight and trim the ends.
You now have a "stop" at the end, and your hand will not slip off.
I hope this helps
Take care