One issue I've found with this is the default or first value: you'll quickly find the number of leads with this value goes up as sales reps quickly put in whatever they can. To avoid this, you might have a default value of "unknown" or "other" and then monitor who uses these values. Sometimes this indicates you need to add another value to your list, other times it means the rep just doesn't want to put in perfect data. Either way, its better to have unknown as a value than data that is possibly wrong.