I switched to the new Verizon plan last evening, allowing the carry over of unused data, but didn't opt for the safety mode.
After adding Xfinity home wifi a few months ago, I dropped my data plan to 4GB, to cover cellular data usage on the IPad and phone when I am away from home for short periods.
When I am
traveling I can increase to 6 or 8GB, then drop it back when I return and the home wifi picks up.
I always leave on an extended trip with plenty of e-books downloaded, and just shift into a "read more, tv less" mode for that time period.
If I have a tv signal, great...if I don't, doing without is fine, too.
Maggie