Excellent, they're really good for coral colour. They're what a lot of the better coral shops use to show off the colours. :smiley:
Ideally, you'd have a DSLR camera and use that as a light meter to match the output of the AI Sol to that of your halides by measuring either the incident or reflected light, but incident will be easier and more accurate. If you've not got one, then just go by eye and try to get it roughly the same. Don't forget that height over the tank has a massive effect on brightness too, as light follows the inverse square law as it dissipates. So twice the distance is 1/4 the light intensity, etc.
The metal halides are pretty bright though, so there won't be a huge light acclimation needed, like if you were going from 2x T5s to a 250w halide or the LEDs.
I got the sat nav kit for the Rex. :)