What are the disadvantages of dual-powered lights (like the ones described in the link below) compared to having two lights?

http://www.rostronics.com/proddetail.asp?prod=1200Wdual2softboxkit

Other than the obvious of not being able to put it in two places at once, is it just as good as having a 300 and a 600 watt light?

Thanks for your help.

I honestly can't see any downside, but then, I haven't used these lights. They look ok, and it sounds like a decent idea to me. Of course, as I tried to go back to take a second look, the site refused the connection.

From the pictures, it looks like those lights would only be good to use diffused or as a backlight. Two bulbs means two filaments and a softer shadow or even a double shadow when used without diffusion.

In terms of output, they seem pretty versitle in that the heads are "2 lights in 1", but they look to me like glorified Home Depot work lights. I could be wrong about these lights, but Home Depot lights have a really dirty pattern instead of a clean spread like a fresnel or open face. Notice that the reflectors look like that of work lights as opposed to a parabolic shape. That said, I think these lights would still work well with the softbox on.

I'm not an expert by any stretch, however, I just happened to plug in all three of my new lights from Britek/Rostronics (a 250, a 300/600, and a 500/1000), and indeed, the one great thing about these lights is the inexpensive soft box that they all support (not the easiest to throw together according to those that have used the Chimeras, but the glow and throw was quite nice!). As far as the difference between running it at 300 vs. 600, well, it didn't seem to double the lumen/output, though I don't know if the logic of double wattage=double luminous output is... um, logical. The "focus" control seems fairly useless, but then again I haven't received my Arri Fresnel yet and have never actually used a focusable light before.

Overall they seem like a great low cost addition to any kit (especially and perhaps primarily, when used for diffusion), and also the barn doors come with clips attached to the doors for gels, etc. The back casings are plastic, though durable quality, but plastic nonetheless.

Well, if you want to read a bazillion other comments on the Britek/Rostronic stuff, pop on over to dvxuser.com as this is where you'll find a large and supportive audience for the Britek line, with fairly honest assessments of the quality:

http://www.dvxuser.com/V3/showthread.php?t=20208&highlight=rostronics

or just query 'rostronics' and/or 'Britek' from the search and you'll find a number of threads.

The dual does allow some flexibility in light position.The pattern is good ,no apparent "holes".The barndoors are excellent.They are WAY far from work lights,they actually run very cool .They cool down fast for packup,have safety wires with them.And I agree with the softbox on its nice even source
You can't get away with fewer lights but the dual does add versatility.
Ive checked the output difference with 1 lamp versus 2 and it does double output (read 1 stop exposure change)

Jack, thanks for that additional info. So, what's the formula used to assess actual additional luminance, I mean, 300 to 600 gains one stop, but that's not to say that going from 100w to 200w would also gain a stop, right? Just wondering if there's a formal calculation, or general rule. Thx.

One stop represents either twice the light or half the light.the quantity makes no difference.Did I say that outloud? The amount of light makes a difference in your scene but once you have exposed for that quantity cutting it in half would require you to open up 1 stop for equal exposure.whether 200w versus 100w...... or ........ 2000w versus 1000w.