This is definitely a good idea.. currently i recommend that anyone who needs to do stuff like this should make sure to configure a fast external graphics editor for use with screenshot captor.
When you configure it in the SC options you will see a nice button on the toolbar of SC that you can just click to quickly edit a picture, then just save and it will automatically show up refreshed in SC after you save it.
It's designed to make it really convenient to do advanced editing in conjunction with SC.