Hey Dave, I can tell you how to raise the max input voltage from ~12V up to somewhere around 16V, if you want.
It just involved removing one component (the input MOSFET) and making a solder bridge between two pads. It will defeat the input polarity protection, but I think you're probably careful enough
BTW, the whole reason I haven't made it past 12V input protection is the availability of a suitable MOSFET for the job. The one I use has a combination of characteristics that allow for a versatile range of input voltages, but maxes at 12V. There are some that will do 20V+, but the minimum input voltage is around 4-5V or so, meaning that if someone wanted to run an IR diode, it may not work... so I just stick with the one I have.
EDIT: nevermind, guess you did that already... I didn't read entirely through to the latest posts