It's a single stage urethane. If you use a metallic color, do not plan on sanding the paint. If you do, chances are that you will be left with a "blotchy" paint job. Basically, you'll be sanding through coats of paint, and unless they are perfectly mixed and applied at the same distance with the same pressue, which is almost impossible, you will get small inconsistencies that will show when you color sand. Basically the paint will look like it has light and dark spots from where you sand through layers of paint.
Omni is affordable and relatively easy to apply but for a couple hundred more you can have a base/clear job, that will last much longer and shine more. The last time I sprayed Omni was 2 years ago on an S-10 and the paint is failing in several spots. If it's a puff and scuff, and sell job, then Omni is the way to go, otherwise go with what the majority of auto manufacturers use on new cars. (Base/ clear)
Good Luck!!!