I'm on Verizon with an 822 and a Family Shared Plan (6 GB between me and my wife - she uses about a gig on her Trophy, and I use the rest). I tether just fine. No Verizon Windows Phone has ever been hacked to make tethering work without them knowing it, that I'm aware of, or I'd have been doing it, but since Tango it was enabled in the Trophy, and that's when I switched to the shared plan from the unlimited. The question is do you really need the unlimited? Switching from what I had (something like 3 phones, one basic phone and two Trophies with unlimited data on a 1400 minute and unlimited text shared plan) to the shared plan with 6GB and unlimited minutes and text ended up saving me about $30 a month, I think (and I have a corporate discount). The only difference now is that at the end of my billing cycle, if I go over, I add an extra 2 gigs to the plan, which costs $10, rather than pay $15 for 1 gig of overage. Then at the start of the next month, I switch it back.
So really, it's not worth all the whining, unless you're really a data hog - and I know that I use quite a bit - I tether a lot.