I have compared both the MS and Piko side by side as well and had the opposite conclusion.The Piko was considerably brighter than my MS on full power.Maybe i have a bad MS,or you a bad Piko.Were both lights cool when making your comparison as the Piko will power down quite quickly?.
The way I think of it: lumens is total light output. lux is light output per area. given the same led, a light with a spot reflector will produce a higher lux reading than the same led with a flood reflector.
I find lux ratings to be less meaningful to me than measured lumens. the problem is that accurate lumen measurement is expensive while lux measurement is cheap enough that I can do it....
edit: I should add that having both measured lumens and measure lux is ideal, giving and idea of overall brightness and spot intensity.