When adding some comment on a talk page you have to click 3 times to insert your signature. People that've never used VE and used to stick to the OWE, would probably have to click more just to locate it while using NWE for the first time. So my suggestion is to take the signature button out of the "insert" dialog and put it directly on the panel so that it would become accessible in a single click.
I think this inconvenience might prevent some interested users from using the beta feature.
And please consider adding two hyphens in front of the four tildes, just like in the standard signature.