I have a couple of step-up rings (67mm and 72mm up to 77mm). No issues with vignetting. One problem is that, with rare exceptions, a step-up ring and larger filter precludes use of the lens hood, meaning less contrast, more flare, and less protection. They also tend to get stuck, so have a set of filter wrenches.
Baffles can help here, as can an extra hand by itself or holding a card/hat/etc to keep out stray light.
The hood isn't the only way to block out incident light. Just look at the baffles used in hollywood.
Can you point me to any alternate "hoods" that would screw into an 82mm filter thread? I have a Mamiya rubber lens hood that screws into a 77mm filter thread but that one is for longer lenses. I use it for shooting hockey with my 70-200mm and 7D... I especially like it if I'm ever shooting through the glass... I can put it right up the glass and if the players hit the boards or someone bumps me it has some give so I won't get a black eye!