I have a simple windows service, that might need to be configured on-the-fly (a COM port to listen to). I have done the UI as a console app that connects to the windows service through WCF, it works and fun.
Question: Is it a good idea to develop a MMC Snap-in to control the windows service? Would it be cool?
Note: I haven't done anything with MMC before. I can do .NET C#, COM, C++ but would like to stay within C#.
MMC Snap-in: Cool? Sure. Necessary? Not so much. If you've got a desire to learn how to develop MMC snapins, this could be a great excuse. If you just want to get it done, I don't think I'd go that route.
Windows Services can accept commands from outside while running. I'd just send data into the service with the new COM port. I'd also test this with your console app to make sure it releases the first COM port properly. A windows service communicating with a COM port can lead to resource locking issues.