Good start!you mean MONO, as in .NET application? => does it compile under win/linux too?
I use serial tools for Mac (it's available through the programmer's website) native application in Objective-C. It does what's expected... although, I'd like to have the ability to change the string terminator like in the Arduino interface. But you can't have everything... Will you implement that on your version? That would be the push to try it.
Automatic word wrap is another. If I remember correctly, both the word wrap and send on the Serial Tools software are missing. So the data is sent as I type, instead of when I push "Send" or Enter. Which is where the line terminator (none, Line Feed, Carriage Return, both) comes in handy.