Rastoff
US Veteran
It’s ironic that this topic has come up. I was, just days ago, questioning this very thing. I have an old, 5- D cell Maglite ( left over from LEO day’s), that I would love to convert to led.
As I stated earlier, if you feel the need to have a club, upgrading the 5 cell Maglite makes perfect sense. In some places it's illegal to carry a club. It's legal everywhere to carry a flashlight.TerraLUX by Lightstar Maglite Ultimate LED Conversion Kit, 1, 000 Lumens, White Light, 4 Hours Runtime - For 4-6 Cell D Mag-Lite Flashlights - MiniStar31M-EX - - Amazon.com
This one, which has three LEDs, is the only one I have found that is worth fooling with, but it's for 3-6 cell Maglites only.

The 3 led kit you linked to costs $40 and then you need the flashlight which will run at least another $30.
This one only costs $29...
...and is the size of my palm. I can carry it everyday without issue. It's got three different light outputs; 350 lumens, 40 lumens and strobe. It can be programmed so you don't get the strobe if you don't want it. 40 lumens is perfect for everyday use to find whatever you dropped or see inside your engine compartment or whatever. 350 is great for blinding the attacker that everyone seems to love so much. I don't like the strobe, but it could be valuable in certain situations.