@donrhummy -- Mine took 23h 59m. I began the port at 5:11pm and received notice from Google of success at 5:10pm the following day.
I have had zero complaints or comments from the people I call on Skype (using either my old iPhone or my N4), and I ask all the time if they can hear me OK, does it sound OK, etc., and my wifi speeds are nowhere near yours. I've been really happy with Skype, but I've heard good things about the Vonage app too and am thinking I may give it a try just for the heck of it.
With respect to the Obi, the call quality is outstanding (I have an Obi202), even with a cheap $19 Vtech handset attached. My Obi is plugged into a switch (not directly into the router), so it's not wireless, although Obi does offer a wireless adapter. I haven't figured out how to configure it to work directly with Skype, so for now, calls that come in on the SkypeIn number are forwarded to my GV number. It would be nice to be able to distinguish the call source, but that's what caller ID is for, right?
@tpd15 -- If I use the GV app on my N4 for SMS, the recipient sees and replies to my GV#. If I use the native messaging app, they see and reply to my T-mobile cell phone number. I have GV configured to use the native messaging app, but for some reason it doesn't. I don't like the GV SMS interface at all, and hate that there's no MMS. Suggestions welcome!