Welcome, Freshman. This is a neat place to be.
I don't have any experience with the Princeton Tec or the Propolymer, but I added a Xenon bulb to my new Mag 3 D cell, and it increased the brightness about an observable 15-20%. If they make Xenon bulbs for 2D cells, it would likely increase the brightness a like amount.
I am now waiting for my heatsink and emitter, to see if I can make the Mag sit up and SHINE /ubbthreads/images/graemlins/grin.gif
From the LED replacement light section at Flashlightreviews.com, The Diamond Lambertian regulated replacement bulbs improved the output of a 2 D cell light by a significant amount. The 3 D cell light output didn't improve much, but the service life/battery run time are said to be increased.
I'm considering the 2D replacement bulb for a service issue angle head light, if I don't buy the UK 4AA LED angle head light. It looks like it may do as good a job, weigh and cost less. More later. /ubbthreads/images/graemlins/broke.gif /ubbthreads/images/graemlins/smile.gif /ubbthreads/images/graemlins/grin.gif