Agree that it might not be worth it to update that host.
While there may be some preceived value in reusing the existing flashlights, there's really not much value of the mag body, especially considering if you are planning on budget is going to be in the range of $50+ or more/light.
One question to ask, if you were to disregard imagined "cost savings", would your boss pick the Mag4D body again for some other factors (maybe you have a stockpile of batteries)? LEDs are now efficient enough that CR123 or smaller battery type will give you a brighter and longer runtimes than incan. Mags all in a much smaller lighter package.
Point is, if you're going to spend in the range of $50/light don't feel that you should reuse the 4D bodies because reusing something is supposed to be cheaper.
If price is a concern driving the upgrade, probably take a look at dealextreme or kaidomain for some relatively inexpensive lights that use modern LEDs.
In the long run, if these lights are going to be used at all, it's the batteries that should end up being your main cost. Take a look at choices that have multimode as using low mode will extend runtime==less batteries==less cost.