as others have said (in so many words), the legitamacy of what you should do (as opposed to what you can do - which is pretty much anything), revolves around the ethics of:
1) are you stealing work from your employer
2) are you stealing material from your employer.
2 is the lowest form, but 1 (in my mind) is the really ethical question, and the transparancy of what you are doing can also set you apart from bottom feeders, since it is most polite to simply tell your boss what you are doing. Although some might consider this to be foolish, if your intent is to grow your business, you and your employer could actually benefit from the arrangement rather than mutually self destruct your ties. For example, if you were to concentrate on a type of work that your employer regularly shuns, you and your employer have several options should your business grow:
- you could start a new division with a more lucrative result for you and your employer
- you could subcontract and while making more money, your former employer could still use you when needed and make a profit off of your work (and you could refer other work that you might not be interested in back to your employer).
Of course, a lot (most) employer/employee relationships would not turn out as indicated above, due to the shortsightedness, greed, stupidity, etc. of displayed by most folks; nevertheless, if you are fortunate to work for a savvy employer, and you yourself have the intestinal fortitude to take the high road, it remains in the realm of real possibility, and you would not be the first to take this road and make it a win-win instead of a dog-eat-dog situation.