This is always a touchy case, but are you quite sure you are announcing reasonable numbers?
For high-selling shareware for Mac, you're assuming that one will approximatively sell 2660 copies per month? For a $10 software, that would be over $300.000 a year? Let's be reasonable; these numbers are not true. Highly popular shareware on PC will sell at very most 3000 copies per month, so it would always be less, and much less for any shareware for Mac. Do you sell as much as 2500 copies of your Moon software?
This is always a touchy subject, and I believe no one really answers honestly; but that article could lead people to start shareware business because it looks so profitable. The shareware industry is by no means a "get-rich-quick" idea, and I think you got your numbers a little exaggerated here.