I live in a rural 3G only area and have excellent service on my 3G mobile broadband modem. However I pay $59.99 for 5G with $0.05/MB (it was $0.25/mb until Verizon changed for me) or $50. for each additional GB, but much better than the old $250./MB.
To get the 5G plan for $50 plus $10/GB, Verizon requires an upgrade to the new 4G mobile broadband modems. However, the customer reviews on Verizon Wireless show that both of these devices have very high disconnect rates in 3G only rural areas. Thus you can not get the cheaper rate plan without giving up reliable service for high disconnect service. Rural areas should be allowed to just change to these rate plans until there is a modem that works in 3G only areas. I tried to do this but the system does not allow the customer service person to do that change.
I am in the same boat as you. My modem and 3G is working great (tower is only about a mile away...can see the light blinking at night from our backyard). I'm just afraid if I upgrade to one of the modems that is 'compatible' w/ 3G, it won't work as well. I do love the thought of paying 10 bucks less a month though.