All this talk of lumens, I think some clarification is needed. The physics of light are complicated, but essentially, lumens aren't the right measure of light for photography purposes.
Lumens measure the total light in the beam of a light source. It's a great way to compare two different lights of the same type, which is why it's required to list the ANSI lumen rating on almost all flashlights, lightbulbs, etc.
What's important to photography is the incident light on a scene (ignoring the complex reflectances of each object), which is measured in lux. A 1000 lumen flashlight will cast more lux onto an object than a 1000 lumen light bulb at the same distance, because a flashlight gives more light per unit of solid angle, measured in candelas. Of course, the distance of the light source also greatly affects lux. (Remember the inverse-square law?)
So don't say "1000 lumens is not enough" because it doesn't specify how much of that light is hitting the scene and being reflected into the camera.
That said, you can't ignore the uncalibrated, inconsistent color temperature of almost all flashlights, as well as the downsides of having a point light source (hard shadows, etc.). "Pro" photo/video (ie. expensive) lights and diffusers/modifiers are better, but the question will always be what's good enough for you. With a lot of experimentation, you could get good results from any light source.