I used to have a Wifi Broadband account with Verizon. It was always very painful when I was trying to connect with it while traveling on bus or train etc. I always had complaint about the connection. I was never able to maintain a stable connection for long period of time. So recently I switched on using smartphone Droid X and subscribed to $20/month tether plan as well. No I do not want to root my phone and deal with Verizon if they decide to shut down my service. It is not just worth it for me to loose the service when I am in middle of some important task while connected to file servers or things like that.
This morning was one of those days when I had to absolutely connect to a remote server via RDP while I was travelling on bus. Not only that, I had to run few high traffic sites as well with it. I was very skeptical at first about battery life, connection stability and quality of connection. Well, to say the least. I was very impressed with tether service I got out of my Droid X. I was connected for about hour and half. I never lost the connection. It only drained about 10% of battery in that period and connection speed was very good as well.
Overall I would say my decision to get rid of broadband account and use tether with Droid X was not bad at all and it paid of in one day only.