Even then, any kind of service outage means that you longer have a phone you can use during an emergency. Granted, most of us could reach for a cell phone in that situation, but if you're concerned about 911 accessibility, you might want to stick with your landline (which is immune to power and Internet outages).
Ditching your landline may also mean ditching your phone number: Google Voice, MagicJack, and NetTalk don't yet allow you to port an existing number, though all three services say that this option is in the works). If you want to keep your old, familiar digits, you'll have to choose Ooma.
Or not. In recent years, cable and DSL services have stepped up with competitive offerings, often bundling phone service with TV and Internet packages for much less than the telcos charge for phone service alone. Indeed, many homeowners may find it more convenient to pay those few extra bucks a month and keep everything under one umbrella.
I toyed with that idea myself, but in the end I went with Ooma. It delivered better call quality and a much nicer Web control panel than Vonage, and it'll end up saving me around $300 per year, even with the Premier package. I may not have banished my phone bill entirely, but I've definitely cut it down to size--and got a better service out of the deal.