Was hoping all these replies were discussing the topic, as I am somewhat interested and wanted to hear other peoples thoughts. I currently pay about $235 a month on T-Mobile with 4 lines, with 2 lines having unlimited data and the other 2 at 2 gigs of data a month (parents have the last 2 and they don't really need data).
I know at times I've gone well over 10 gigs, but I'm not sure if I've ever gone over 20. I would likely pay an extra $10 a month for $20 on my line if I paid significantly less than $235.