Verizon is (deliberately) obscure about this particular situation. I'm in the same position as you and as you stated my unlimited data carried over to the Razr Maxx. However, I also have a mobile hotspot device that I use for an iPad, a Kindle Fire, and a laptop when I need it. That contract doesn't expire until the end of this year so I don't want to discontinue that service and switch to tethering until that time.
I've checked the VZW website and, as I said, they clearly don't want to talk about this situation. Instead, you can add tethering to one of the currently available limited plans for $20 per month. This provides an additional 2 gigs per month on the data plan but that's obviously meaningless if you can add the feature to an unlimited plan.
As a sidenote, it appears that Verizon provided additional download capacity as a result of threats from the FCC to investigate a surcharge for tethering for data you've already purchased. By charging the same $20 surcharge but throwing in an additional 2 gigs of data cap they avoid this problem.
Anyhow, I specifically asked whether I could add the tethering capability to my unlimited data plan when I purchased the Razr Maxx and was assured I could. I don't necessarily believe that, of course. Between ignorance and deliberate lies it's always difficult to tell if you're getting the straight scoop from Verizon until you're prepared to actually make a plan change.
I have a feeling that when I'm ready to add tethering to my data plan they will try to force me into a tiered data plan in the process but we'll see. Since I almost never come close to using the full five gigs on my mobile hotspot each month, I suspect it will not make much difference to me but I will find it annoying if it happens.
