I fitted the led upgrade to our d cells and they work pretty good. i also got the three aa cell maglite with their led in and its excellent lightwise. for close up work I use a gerber infinity or recon. single aa and nice and compact 
the nite ize upgrade is ok I got a different switch for my two cell as I didn't like the nite ize one. had one set of bulbs fail one by one till I ended up with 1 working led and after a while they seemed to go to a bluey light as the batteries fail. the proper led maglites are single bulb with a proper focus and much brighter.

the nite ize upgrade is ok I got a different switch for my two cell as I didn't like the nite ize one. had one set of bulbs fail one by one till I ended up with 1 working led and after a while they seemed to go to a bluey light as the batteries fail. the proper led maglites are single bulb with a proper focus and much brighter.