I think that high quality low powered variables are superior choices for general purpose rifles.
Dedicated CQB weapons are best served with 1X optics, preferably with long battery life. While 1X optics can be used successfully out to 300 meters, they shine at closer ranges.
Fixed 3X to 4X optics are good to go from about 25 out to the limits of their reticles. The ACOG line dominates this sector of the market, so most of my comments about the low-powered fixed optics are about them. They can be used at much closer ranges but reticle brightness when in transient lighting is sub-optimal. In even lighting they are easily used at CQB distances, which can be a bit deceptive in their real-world employment. I am not a big fan of them, but some reticles lend themselves very well to general purpose use.
Take a look at the stickies in the optics forum, there is a lot of good info there with regard to the low-powered variable options as they currently exist.

