I am not sure if I am missing something here.

I downloaded and used it for a while before I tried the SIP solution with GoogleVoice.
http://talk.maemo.org/showthread.php?t=80505

The SIP solution allows me to receive calls and dial out using my GoogleVoice over wireless or data service.
It's quality over wireless is very good and over data service, it is not that bad.
It shows your GoogleVoice number as caller id.
It integrates with your contact so you can call any number from your contact using cell or sip any time.
It is easy to change status to online/offline
The simonics gateway seems to be very reliable.
It is totally integrated with N9 interface and available always without having to run another app.

So what am I missing? What does this program gives me that the SIP solution does not?