Wow. Really? I wasn't sure they were since the ratings are a bit different, and the Klarus doesn't have the SOS or beacon.
You are right, there are some feature differences, which I think are minor but might be more important to other people.
The MiX6 has M-L-H-Str mode sequence, which is different than the L-M-H Revo sequence.
I don't think the ratings are different enough to perceive with the eyes.
The Klarus is lower priced than the Revo.
According to the selfbuilt review, the MiX6 head will screw onto the Revo body and work.
He also says that the drivers are "very similar", both using current-regulation and behaving about the same.
I think they are basically the same light, with some minor differences so that they aren't called "copies" of each other.
If these small differences are not a deal-breaker, you can get the SS MiX6 for about the same money as the aluminum Revo. Or you can get a Ti MiX6 for just a little less than the SS Revo.
I mentioned it because if you can't get a Revo, you can get basically the same thing from Klarus, with minor variations.