[Andrew]

The data used syncing OmniFocus is _usually_ not very much - actions are small. Things I can think of that would impact that would be when initially setting up syncing if you have a large database; if you often include attachments in your actions; or if you get into a situation where you have a connection that is unreliable enough that OmniFocus never/rarely is able to actually successfully complete sync attempts. I don't have a specific data estimate, however. (My personal total data usage is typically a few hundred megabytes each month, because most of the time I'm on wifi. OmniFocus is only a small part of that total, and I'm a relatively light OmniFocus user.)

As for how Verizon might improve on their deal: there are no guarantees, but in the past the phone models got pushed down. If that happens again this time, the 4S would take the place of the 4 in the lineup and the 4 would be dropped completely. In that case, you would likely be able to get the same deal as Verizon is offering for the 4, but have it include the 4S instead. (However, some rumors suggest that this year Apple might come out with a different lower-end phone to replace the 4 and/or 4s with.) But I don't have any privileged information and I can't promise just what either Apple or Verizon would do.