Update: the porting process completely worked.

My Verizon account reports that my monthly bill is now $51 rather than the original $107 (that's after my 20% employer-negotiated discount, and we're talking about only one line rather than the original family plan). FYI, the new T-Mobile bill for two smartphones (one with 2.5GB of data, one with 500MB) and a tablet (at the freebie level with 200MB) is going to come out roughly the same as what I was spending on my original Verizon plan, with one smartphone and one dumb featurephone.

Also of note, I'm running my first-ever eBay auction. I set it up for seven days, no minimum bid. For the first five days, nothing. Now there are two bidders duking it out and it's up to $100 with almost two days left. This suggests I might well hit the $250-300 that I've seen on other auctions. I can also sell my Galaxy Nexus after this auction completes and I've sold off my old line.

Suffice to say that I'm entirely happy that leaving Verizon turns out to be a profitable maneuver rather than being forced to pay an early termination fee.

As to the quality of T-Mobile, I'm largely satisfied with it outdoors. It's inside that it's got serious problems. I'm hoping I can find somebody competent at T-Mobile to present with all my measurements. That's still work in progress.