The knock on three blade props is that they present more "frontal area" to water flow. The same is said of two blade fixed props to a lesser degree.
Being a basically cheap person, I tend to defend fixed propellers by citing the following points:
1. They cost a lot less.
2. They never fail to "open"
3. They have the absolute minimum parts count.
Absolute performance sailing may dictate a folding or feathering prop, but I take special comfort in my fixed blades when it is dark, foggy or raining and I am in close with the shore.
That said, I have a three blade prop on my powerboat and a two blade one on my 30' sailboat. If properly sized, I don't think you would be able to tell the difference, except that a two blade sailing prop probably yields a little less drag.