I have both the Opalec and several Luxeon Stars (LS) lights, and use them both.
The Opalec is nowhere near as bright as a LS.
Does not mean it is a bad light.
For applications that you were using a mini-mag, the Opalec is probably a much better choice.
I find that people use mini-mags for "arms length" applications, or for general illumination 5-15 feet in front of them, and for those applications, the Opalec puts out a pure, broad, even white light.
But, to compare the LS to the Opalec, the LS will be, from 5-20 times brighter than the Opalec, depending on who made it.
It's like comparing a bike to a motorcycle. The motorcycle is much much faster, but it doesn't mean the bike is no good!