I've read some mixed comments online about the Kirk BH-1, and thought it was time to share my experience the ballhead.
I bought the Kirk BH-1 in early 2003. I've had it more than long enough to know it well, and to have given it a few dings and wear off a bit of finish. It works just like it did the day I unwrapped it, even if it isn't quite as nice looking. It is very solid. I have confidence that it will hold anything I can put on it. In a nutshell, it works very well and I like it. I have never regretted the purchase. It works and doesn't get in my way; I generally give it no thought in use and that's the way it should be. I've had other heads that would shift, slip, or poke me, so having something so well made is wonderful. My version is old enough that Kirk changed the clamp design, but I'm not sure if anything else is different vs the current model.
Prior to the BH-1, I had a Bogen/Manfrotto 3038 heavy ballhead. The 3038 was very strong, but not smooth, and so heavy that I did not carry my tripod as often as I should. The raves about Arca-Swiss style heads convinced me to upgrade.
One of the reasons I picked the Kirk over other models (such as the Arca-Swiss B1), was the orientation of the drop notch. Many competing models had the controls on the wrong side relative to the drop notch. I hold the camera with my right hand, so I want the ballhead controls easily usable with my left, with the drop notch opposite from me. I shoot a lot of closeups, and end up aiming down frequently. Only subsequent to my purchase have other brands followed that model.
Also, around the time I bought the BH-1, the Arca-Swiss B1 was notorious for having lockup problems. My Kirk BH-1 has never had a single problem in operation, and I've used it in every type of weather. As I'm sure most of you know, Arca-Swiss has since resolved the lockup issue.
At about 2 lbs, the BH-1 is half the weight of my old Bogen, much smoother, and though I didn't want to admit it, the plates are much easier to deal with than the Bogen hex plates. For the life of me, I cannot understand why Manfrotto has not completely switched to A-S plates (As of 2013, they support a number of quick release systems. Hey, late breaking news: http://www.the-digital-picture.com/News/News-Post.aspx?News=7236.) With all the more recent advances in ballheads since I bought mine, 2 lbs probably sounds heavy to a lot of people, but the weight certainly falls into an acceptable range where I don't mind hiking with it.
My model is old enough that the clamp does not have any provision for safety stops, nor a level. I simply have to make sure I clamp it down properly. I have a knob release (I am not sure levers existed when I bought it). I have not had any accidents, the clamp is simple and strong.
How strong is it? Once locked, the BH-1 doesn't budge, not one bit. There is zero creep (though there is settling as you let go, like in all such systems, this is expected and normal). I have never seen a single movement while locked down in 10 years of use. Odd angles? I'd be more concerned about the tripod tipping over than creep. I've had up to a 400mm f/4 on it and it gives just as much confidence with that gear as it does with a compact setup like a Minolta XD-11 with a 50mm (yes, I was shooting film when I bought the BH-1). I've never even stressed the BH-1. Current models are rated at 50 lbs, but I don't recall seeing a rating when I bought mine. Photographers with heavier gear than mine were using this head when I bought it, so I wasn't worried.
How smooth is it? When the tension is on the looser side, it is quite smooth. It beats everything else I have personally used, but I haven't compared it against many other models so I can't say if one of the others is smoother or not. A number of other reviews I've read claim that there are a few models that are smoother, but if true, I'd say it isn't a concern if you use the ball loose and lock it down tight. If you use your ballhead loose, you'll be happy. I read one review that said the BH-1 is not smooth. All I can say is, my 10 year old model is smooth. However, the BH-1 isn't as smooth when the tension is set fairly tight, and clearly the ball isn't as perfectly round as one might expect. As you move the ball around, the resistance increases and decreases. That reviewer might have a lemon, or perhaps he was trying to use a lot of tension.
For years, I simply left the tension setting fairly loose, relying on the main knob to tighten the ball. I never gave the tension knob any thought. More recently, I've read about people setting tension on their ballheads so that the ball does not slip even when the main knob is loose. I tried this recently, and found it just isn't workable on my BH-1. The tension knob requires several complete revolutions to go from completely loose to completely tight (so tight you can't move a thing). But the transition from loose to tight is very very short and sudden, and I have not found that "just so" tension setting. The tension control knob is not marked and not indexed, and it is also very easy to turn. My kids change the tension on me all the time. As a result, I expect some of you will decide to pass on the Kirk. This is the one part that Kirk could really stand to improve (maybe they did?). For my use it isn't an issue. FWIW, a close friend has a Really Right Stuff BH-55 and says the tension isn't very workable on that model either. Only the Markins and Arca-Swiss users seem to rely on that feature, from the bit I've read online.
Also, with the tension set fairly high, I found that the BH-1 ball will shift when I tighten the main control, changing the composition (not just settling), depending on the angle. In doing closeups, this is unacceptable, so I just keep it loose. I can't tell you if that is just my copy, or a common design issue. I've read of this shifting/pulling with other brands too. I get the feeling that only a couple of the very highest end ballheads don't have this issue.
The panning knob just works. Loosen it to pan or adjust the location of the drop-notch, tighten it. It moves smoothly and locks tightly. I've carried it over my shoulder with a camera mounted and it has never come loose. No worries.
The bottom line is, this ballhead holds my camera steady with every piece of gear I've ever owned. The BH-1 isn't fancy, but it is a workhorse. It works well enough that I generally don't have to think about it when I use it, which is as it should be. Compared to previous heads I've used, that was a first.