Only reason to keep with a Maglites is if you want to walk around with a trucheon. When you can get a 5200 lumen Thorfire BLF Q8 for £35, spending the same on two led drop in bulbs (200 lumen) for the maglites makes little sense.
I too have a few maglites I'm reluctant to throw out. If you go down this route you can buy battery cages that'll allow you to use AA instead of the expensive D cell batteries