Honestly it's a waste of money. Do the math on it - you're essentiallly paying twice for your phone.
When you buy a subsidized phone and put under contract, you're paying X amount per amount and by the time your contract ends, the carrier has made back the amount it subsidized. However, when your contract is up, your monthly price stays the same, it doesn't get lowered to what it should be because the subsidy is payed off.
Under the edge plan, you're still paying the same price per month for the plan in addition to yet another fee by Verizon. Just another way for them to collect even more of your money for essentially doing nothing.
In your particular case, if you aren't looking at switching carriers in the next two years - financially it's to your benefit to purchase a subsidized phone and renew your contract but avoid the edge plan.