Originally Posted by
cyccommute
You are off by a factor of over 2 in the efficiency of the MR16. At nominal voltage (12V), an MR16 puts out around 40 lumens/W. At 20% overvoltage, it puts out up to 70 lm/W. Follow acroy's link.
"NLPIP tested several MR16 samples to determine their efficacy. Efficacies ranged from 12 to 15 lumens per watt."
http://www.lrc.rpi.edu/programs/nlpi...erformance.asp
I guess it's case of YMMV.