Redhead lights are certainly very useful, though the cheap knockoffs tend to suck power and not give you quite the same output strength as you'd normally expect. That said, they're certainly not a bad choice, and will give you options for lighting a scene.
Remember that redheads suck 800w (or ~7 amps) so keep that in mind when plugging them into a household circuit.
Also, they are very hard, directional lighting. You may want to look into a chimera or scrim to soften them a bit. I've also never seen redheads with built in dimmers, but as with any light dimming it warms it up - you're better off keeping it at full strength to keep the colour temperature at 3200k, and then softening/diffusing/scrimming to 'dim' your output, unless you want a warmer look/feel.
Also some safety tips to keep in mind with open-face lights: They get really, really hot. You may (see: should) want to invest in some gloves to allow you to move the light, and move the barn doors while it's on. Be careful of moving the light when it's on - it's better to turn it off, move it, and then re-strike to save issues with the bulb.
Always attach gels to the barn doors, and put as much distance between the gel and the face of the light as possible - the barn doors I generally use have clips on them that you can attach steel coat hangers to, and then peg gels onto the coat hangers. If you're pegging to the barn door itself, peg the gel so it hangs around the outside, rather than gelling close to the face of the light (as I've seen inexperienced gaffers do).
Always put a sandbag on the light stand, and run the cable underneath the stand so as to avoid 'clothes-lineing' of the cable. Always run cables clean, even if it means you have to buy extra stingers (power extension leads), and never have a light cable clothes lineing.
If you're using a chimera or softbox, make sure you don't cover the back of the light, especially the vents at the back, also try and allow as much 'breathing space' as possible. If you leave a softbox attached to a redhead for a longer period of time, it's quite likely that it will start to burn. It's pretty much happened to all of us, so don't get too disheartened. Do keep it in mind, however. It can sometimes be good practice to turn a hot open face light off when not in use so that the light and accessories, as well as the room itself doesn't heat up too much. That said, on a cold night shoot, we like to keep the hot lights on to warm us up. Keep in mind that a hot light (especially multiple hot lights) do warm rooms up, so on a particularly hot day (or even just an average day in a smaller room) you might want to take into consideration the extra heat that the lights will create - you don't want to have your crew sweating the whole day.
Don't touch the face of the light, or the bulb itself with your bare hands - oil from your hands will warm the bulb up at different speeds causing it to blow. If you are moving the light head, make sure you use the black knob on the back to turn/move it, rather than trying to hold the light itself.
Redheads make great reflected lights - it's much safer (and creates a much softer, more natural looking light) to reflect them off a surface rather than aiming them directly at an object or person. Also, try and aim them away from people as much as you possibly can - they're finicky things and when the bulbs blow (as they often do), I've seen them completely explode, sending glass flying everywhere. If you've got them behind a scrim, or pointing up to a ceiling it's going to cause much less potential damage than if it was pointed directly at a person. I've also seen fresnel globes explode, but because of the lenses in fresnels, all the glas was kept inside the light itself.
Always allow at least 5 minutes for the light to cool after turning off before packing the light down. After that, the cable should be removed from the power outlet first, before removing the other end from the ballast or light head.
