I've owned my BH1 head for almost 4 years now and it is a beast, I like how just a slight turn backs it off fully so great for quick changes to your composition. It is fully mechanical as well with no grease inside so it won't freeze up on you. With lightweight camera setups it has doesn't really move when backed off but be careful to make sure it is clamped down before you move your tripod, I had my camera drop forward in the early days of using this head, it isn't a fault but just something you need to get used to. With heavier cameras it works a real treat with a little bit of friction to give you that secure feeling I hate it when a ball head goes really loose on you when you back off that knob. I don't have the side bubble level on mine but I am seriously considering getting another BH1 head just so I can have that, I would still use my current one on my other tripod (TR344) but this mainly stays on my TR424L when I need a very stable base for my setup.
I love the freedom the head gives you, if you need to look straight down quickly you can and if you back off both knobs you can move the head at full range and only limited by the tripod legs