If size is not an issue, the ML300 is a great light. Sure, the technology is a little outdated, but it still competes fine with my newer lights. It's built like a tank, and certainly could be used as protection. The run times are awesome on regular alkaline D batteries. However, I would recommend getting rechargeable D batteries for normal use. The runtimes will be less, but if you keep the batteries regularly maintained it should be fine for everyday use, and will save in battery replacement and environmental impact. Some people get Eneloop Pros with the D adaptors. Runtimes will be a fraction, but if prolonged use isn't the need, then that would probably be fine also.
I prefer something a little more "pocketable" for use around the house. I'm loving the Nitecore EA42. I keep it in a drawer right next to the door. Runs on 4 AA batteries, has excellent throw and a better UI. However, my wife sometimes clicks on the wrong button and doesn't want to be bothered "figuring out" the UI on most of my lights. There is something to be said for simple on and off. I'm thinking of getting the ML50 2C light for her. Very "grab and go" for her needs.
And that brings one last thing to consider. A 4D light is huge! I find the 3D to be less cumbersome, but no less formidable. Also, consider whom else may be using it. My wife has no interest in carrying a 3D light, so a 2D or C may be all you need for everyday household use. You can get a 4D as your own toy lol. If cost is an issue, starting with something that it more useful to more people is probably the way to go.