I’m glad I did that tethering experiment; I had to use my cell phone for Internet in anger today after yet another local WISP outage. Big storm, power outages, but also some robustness problems in equipment and/or service. I do have sympathy, the ISP depends on $300 wireless devices installed in trees scattered all over the county.
Anyway my iPhone worked fine for tethering. I put it in an east-facing window. Only one or two dots of service, but my Mac through it was reliable and seemed fast. I didn’t measure but it felt 10Mbps fast, at least. I quickly forgot I was tethered.
Doing my ordinary daily routine my iMac alone seems to use about 100 MB / hour. Call it 1GB a day. My data plan is only 2GB, but with another 2GB carryover that’s good for 3-4 days before it costs money. Overage charges at Verizon are $15/GB, but you can also avoid overage by adjusting your data plan size; no switching cost and it’s retroactive for the whole month. The plan price is about $5/GB.
It’d be $135/month if I wanted to just buy 30GB a month. But I really use more like 100GB / month once you factor in other devices, discretionary downloads, etc. That’d be $450/month (!).
The plan flexibility makes Verizon a pretty good low cost backup option.