We have a 150 on our 24 gallon JBJ Cube. It's pretty good. Make sure you install it correctly and don't overtighten the screws or you'll end up with a cracked mount (there is a spacer I got that was missing because it was used, so I made one, but I didn't realize the spacer was missing until I tried to install it. I didn't actually crack the mount, but I know of others that have. Again, if you have the spacer and install it correctly, I don't think this is a real problem.
The 150 is adequate for a 24, but might be too much for a smaller cube, especially if you aren't going to try to do all SPS (which I don't think I would recommend without rigging up something to process your water a little better).
The only downside I noticed in comparison to the stock lights/hood is that you end up evaporating a lot more water. For a nano that can be real problematic unless you stay on top of it or have an ATO.
