Focusing mechanisms tend to waste a lot of light... Any particular reason you're interested in a focusing light, instead of a light with decent spill light?
I don't like to recommend them, but check out LEDLenser. Only a few of their models are regulated, though.
I have the Led Lenser M1 and P14.
The Led Lenser P14 is not regulated and only uses a resistor to get the lower mode and is focusable like most Led Lensers.
The M1 is regulated and is focusable.
It even has a low mode and strobe function.
The "
M" series of Led Lensers is the
MICROPROCESSOR series that regulates the output for dimming and strobe functions etc.
The only irritation I have found is that it automatically dims when the torch heats up after about five minutes as obviously the torch does not have enough heatsinking because of its small size.
The M1 is a CR123 battery type torch and it will not work on rechargeable RCR123s.
I keep it in my bag as a backup torch and it fits the pocket very easily.
I don't think I would ever buy another CR123 type torch as the batteries are not cheap in small quantaties here in Australia.
Rechargeable batteries are so much more economical IMHO.