I got a call from 2degrees today offering me the $40 pay monthly plan (4GB) for $30 for as long as I stay on the plan. I'm currently on the $30 prepay plan (2.5GB). I've only ever been on prepay, so have no experience with pay monthly... Are there any hidden pitfalls to this switch? Or is this a no-brainer? On the surface it seems like a good deal - same cost, but get 1.5GB more (and unlimited calls, but I don't care about that).

I do also currently have over 10GB rollover, which I assume will be wiped (?), though that's not a huge deal I guess since I should claw it back in no time.