I've tried this software in previous versions and it works as advertised and is stable (last used with 10.3.9)
I've exchanged e-mails with the author and requested compatibility with the SMS application of the Treo 600 or the Messaging (SMS) application of the Treo 650. He did start to work on it for a while updating me on his progress but I suddenly stopped hearing from him. I know the developer busy and this app is only a "hobby" to him but I hope this is one feature he implements in the future.
If you have any requests, e-mail him. he is very responsive.