Carrier?
AT&T definitely will not put you on a tethering plan without losing your data. I switched from Unlimited to the 4GB Tethering plan (data cost went from $30/mo for unlimited to $45/mo for 4GB with tethering) and I'm glad I did. My normal usage is still below 2GB.
verizon. i'm not gonna change my plan...i would rarely ever be using it
Tethering stinks on Verizon anyway, because if you get a call the data is interrupted.
do you have unlimited data? does it really cancel your unlimited data just by turning it onI tether all the time with my verizon phone. Yes you lose data when you get a call, but so what? If it is an important call I take it, and if it isn't then I just send them to voicemail and continue on my data usage.... Unless you are getting calls constantly, it really isn't the end of the world.
Edit: Besides most people don't call me anymore anyway. We text, email, facebook, twitter, etc.... This does not cause me any interuption during my tethering.